Building a race bike.

Posted: Wed May 28, 2014 2:41 pm

OK here is where I will start.

Some of you know that I have been working on one of my bikes Forever. Rolling Eyes

so I decided to put my foot in my mouth
and make it public that I want to sponsor Dennisthemenace for the 15 season. By doing that I knew it would get me to finish the bike, just to save face.
I had never discussed this with him until yesterday.

You should have heard the big guy giggle like a kid on Christmas when I confirmed to him my plans. That Made my day because its exactly how
I feel about the whole deal.

I don't have any pictures at the moment but will tell the plan for the bike.

Dennis races in AHRMA and the rules say that you can run any size of carburetors as long as the cc's of the motor are under 931cc's. Anything over that is limited to 29mm carbs. What a big CHOKE that would be on a fully ported motor with all the goodies.

So my plan is to build the motor to as close to 931cc's as I can and be able to run 35mm CR carbs as per Captains recommendation.

I laid awake last night (as I do most of the time) and decided that since this is my business. I want to showcase my work and will cut the steering stem out of the frame and do the AHM trick of moving it 1" back and 1 degree steeper. This will require a frame jig so off to the steel yard I go today.
So far I have moved the upper shock location to more of an AHM position and braced the frame in all the correct places.

This bike will be getting everything that I make thrown at it starting with a set of the AHM triple clamps and F2 41mm forks with RaceTech internals.
Brakes will be stock parts with SS lines and as big of discs that are allowed on the front.
Wheels will be GL1200 18" Comstar at the front and a widend Comstar at the rear. I would go with 17" wheels but Dennis prefers the 18" hoops so that is what he will get. Hope it works with the chassis change?

Anyway, now I have went a firmly planted my foot in mouth. So wish me luck and feel free to give me some pointers as you see this thread progress.
I should have the chassis done by the end of August and hope that Dennis is healed up from his upcoming shoulder surgery so that he can come to Portland and test the bike at a track day. It won't have the full race version motor in it at that time but the chassis may need some tweaking to suit his needs?

Keep it in a wheelie, Jim

Posted: Wed May 28, 2014 3:00 pm

Sound like a cool project. I am sure you have thought about it, but I expect you should plan for as much adjustability in suspension geometry as possible. Maybe also consider adjustable offset triple clamps?

Posted: Wed May 28, 2014 3:14 pm

petrat wrote:

Sound like a cool project. I am sure you have thought about it, but I expect you should plan for as much adjustability in suspension geometry as possible. Maybe also consider adjustable offset triple clamps?

Yep I have thought of this and will have both the 44mm offset and 50mm offsets AHM clamps or I can put on some Kosman clamps with adjustable offset but they are in the 30mm range so probably won't go that route. The forks will be adjustable and the shocks are Ohlins and I can change the valveing to suit his needs. More options then Dennis has had in the past I believe?

While I have you Darren. After all of the welding that I have done and to come. Should I have the frame stress relieved and heat treated when I'm done????
Thanks for the advise Darren.

Peace, Jim

Posted: Wed May 28, 2014 3:41 pm

JJam wrote:

petrat wrote:

Sound like a cool project. I am sure you have thought about it, but I expect you should plan for as much adjustability in suspension geometry as possible. Maybe also consider adjustable offset triple clamps?

Yep I have thought of this and will have both the 44mm offset and 50mm offsets AHM clamps or I can put on some Kosman clamps with adjustable offset but they are in the 30mm range so probably won't go that route. The forks will be adjustable and the shocks are Ohlins and I can change the valveing to suit his needs. More options then Dennis has had in the past I believe?

While I have you Darren. After all of the welding that I have done and to come. Should I have the frame stress relieved and heat treated when I'm done????
Thanks for the advise Darren.

Peace, Jim

The question should be asked why would you want to "heat treat"? I believe the chemical make up of the frame material is close to say 1020, and so the hardenability is quite low and doesn't respond to heat treatement very well because of the low carbon and alloy content. The transformation it goes through when welding would not see much strength reduction.

What you need to do is just ensure you jig the frame well (restrain) and balance your welds. Stress relieving, which helps to improve fatigue (by reducing the tensile stress imposed on the weld), I think would be pointless since I believe most of your bracing would be predominantly compressively loaded?

Posted: Wed May 28, 2014 4:49 pm

See that's why I asked. I don't know as much as I should but I'm not afraid to ask questions.

Thanks again. one thing is now checked off my list.

Posted: Wed May 28, 2014 4:59 pm

There's never a stupid question .... there are only stupid people that don't ask or do their research, or, who can't get there head out of their ass long enough to see the light.

Twinstar Joined: Nov 13, 2009 Posts: 243 Location: sweden

Very exiting Jim, can't wait to follow your progress.
Good luck!
Regards
Victor

Posted: Wed May 28, 2014 9:48 pm

Jim,
I'm going to try and send you an email with a zip file containing a bunch of pictures of my "Xmas 2013 assembly". Contained in it and amongst everything else are a bunch of close ups of the RSC cylinder barrels being 750 height but 70mm bore. Check them out and ask any questions because these could/maybe the missing link to your program. No doubt we will talk at length about the key pieces to get this project going.

The steering head decision is one of the best you could have made and Dennis won't know what hit him or what he has been missing when he experiences it for the first time, but I know he likes 18 inch stuff but 17 give much wider tyre choices and due to the aspect ratio can have the same diameter. The triple clamps (I wonder where they came from) you may wish to start with the 44 mm version as this will give the slowest steering, (Dennis has stated that his current bike is slower steering) so tread softly here and don't throw to much at him in this area until he feels it first.

All in all it is a great idea and I'll help where I can with anything to get you to be successful and Dennis have the bike to beat.

Captain

Posted: Wed May 28, 2014 9:56 pm

Captain wrote:

Jim,
All in all it is a great idea and I'll help where I can with anything to get you to be successful and Dennis have the bike to beat.
Captain

+1 I love this idea, I just wish I was Dennis....
If there is any way I can help just give me a shout!

Posted: Wed May 28, 2014 11:45 pm

Whatever you do with your frame jig, get the swing arm pivot absolutely parallel to the base plate and the new steering head at a perfect 90 degrees to it......................Without doing this and confirming its accuracy, you devalue everything else you may wish to do in the future. Everything else should be built from these reference points including engine placement (although I doubt it will need adjusting).
Make sure that the rear axle is parallel to the same pivot and have your shock mounts exactly the same distance from the same pivot. Use one of your braced swing arms, brace the frame similar to what I have done and all the above combined will result in a better handling bike than you thought possible.

Now start having fun...........

Captain

Posted: Thu May 29, 2014 1:03 am

Thank you for all the help!!

Just got off the ph with Nathan and he schooled me on the set up. Thank You Nate.

Looks like Dennis's 68.5mm custom Pistons and the 750 crank with 1100 rods and a thick base gasket in copper.
What Nathan just told me finally sunk into my thick skull and made sense.

This is going to cost me but everything I do is for future plans. Hopefully we'll get it right the first time with everyones experience and help?

The plus is I still get to ride it. Very Happy

Didn't make it to the steel yard today. My mill has been bothering me for a month so I tore it apart and the next thing I knew I was spending $350. on nes spindle bearings. It really sucks when a tool is down and you have jobs to do with it. Oh well that's life.

Peace, Jim

Posted: Thu May 29, 2014 1:49 am

As far as the custom pistons go, JE could use mine as a starting point which are 69.50mm. If they go down 1/2mm to 69mm that will get the displacement with a 750 crank to ~927 at a pretty standard bore size. The two rods (a 750F & 900F) I measured are 0.073" different in length, which could be made up by moving the piston pin hole the same distance. All else could remain the same on the piston side. The 1000C cylinder might be able to be decked to 750 height which could give a solid block and the liners could be shortened in case of interference, plus windowed as desired. I think that combination would allow the use of either standard 750 or 1100F power-producing components like rod, crank, cam chains, tensioners, etc. Maybe...

On the 'handling' piece my sole experience was switching from a very good 900F 39mm front end with emulators and 18" bias ply front & rear to a decent F2 front end with stiffer springs and 17" radials front & rear. The front end felt so vague (very light steering inputs) it was spooky and I didn't like it. I'm used to a LOT of front end feedback and effort and it just felt like the front end was skating on ice. I tried the setup a couple of times at track days and though the tires looked good and nothing unusual happened it just didn't give me the feeling I needed in order for me to think I knew what the front end was going to do. I don't know if that's from years of dirt track racing where it's all about keeping the front end doing what you want and letting the back end move around - I'd only be guessing why I didn't like it, but I didn't. The one thing I felt like I was missing was good inputs into my hands from what the front tire was doing. Kind of like some cars with power steering where there's no feeling in the wheel... I can't explain it much more than that. And - honestly - the front end feeling is the thing I worry about the most.

I don't suspect a bias ply 18" tire is anywhere in the same hemisphere as a truly good setup would be, but it's like a habit that may not make sense until some breakthrough or shift in confidence happens...

Regardless, this whole project is going to be a blast and a learning experience! I can't wait - except I have to since my shoulder won't be up to the task for a couple of months. September isn't that far away.

Posted: Thu May 29, 2014 2:07 am

Dennis

why not run 18 inch radials, splits the difference. Gives you the feedback from 18s you like (I prefer it too) but the modern technology of radials. My R runs these, as did my Laverda RGS1000 before it. Bothe were improved immeasurably.

David

Posted: Thu May 29, 2014 2:38 am

nathanhouse wrote:

Captain wrote:

Jim,
All in all it is a great idea and I'll help where I can with anything to get you to be successful and Dennis have the bike to beat.
Captain

+1 I love this idea, I just wish I was Dennis....
If there is any way I can help just give me a shout!

Likewise for me!
If I can help let me know!

Nich

Posted: Thu May 29, 2014 4:37 am

All good ideas. I like Brents solid block idea.
Its got the 750 height so a 750 cam chain will work. It will require swapping out the liners and fitting some 1000c cylinders to have enough room to bore them to fit the new pistons.

I know that the rules state no big blocks but it's essentially not a big block. They wouldn't care if I used 1100 cylinders and sleeved them down but I'm sure they don't want anything that would allow a bigger bore then what came on the largest stock motor. Am I seeing this wrong?

Brent the cylinders in the 750 block that you have are too big to meet my needs but maybe between the two of us we can see if my 1000c cylinders will fit them? I'll get on with pulling the 1000c motor apart and dropping a cylinder out to get the measurements.
If not then I can always have some new liners made.

I'm OK with 18" wheels but not a fan of how heavy the Comstars are. I am looking into some early 18" GSXR 1000 wheels as they came with a 4.5" rear I believe? Plus they allow for an under slung rear caliper which I prefer. I will also have some 17" wheel 's for Dennis to try out. Hopefully the steering head change will make it handle the way he likes? I can always put two stabilizers on it like some of the AHM bikes had.

My heads spinning with how much there is to do but I love the challenge!

Jim

Posted: Thu May 29, 2014 4:42 am

Just a thought but maybe Brent would share his secrete slipper design with me? I may be pushing it. LOL

If not maybe I can copy one of my modern dirt bike pistons? Nathan or Nich, got any ideas?

Hope I can sleep? Is it Christmas yet?

Posted: Thu May 29, 2014 4:49 am

Sounds like a blast. Very Happy

Posted: Thu May 29, 2014 5:32 am

JJam wrote:

All good ideas. I like Brents solid block idea.
Its got the 750 height so a 750 cam chain will work. It will require swapping out the liners and fitting some 1000c cylinders to have enough room to bore them to fit the new pistons.

I know that the rules state no big blocks but it's essentially not a big block. They wouldn't care if I used 1100 cylinders and sleeved them down but I'm sure they don't want anything that would allow a bigger bore then what came on the largest stock motor. Am I seeing this wrong?

Brent the cylinders in the 750 block that you have are too big to meet my needs but maybe between the two of us we can see if my 1000c cylinders will fit them? I'll get on with pulling the 1000c motor apart and dropping a cylinder out to get the measurements.
If not then I can always have some new liners made.

I'm OK with 18" wheels but not a fan of how heavy the Comstars are. I am looking into some early 18" GSXR 1000 wheels as they came with a 4.5" rear I believe? Plus they allow for an under slung rear caliper which I prefer. I will also have some 17" wheel 's for Dennis to try out. Hopefully the steering head change will make it handle the way he likes? I can always put two stabilizers on it like some of the AHM bikes had.

My heads spinning with how much there is to do but I love the challenge!

Jim

Posted: 2014-05-29, 16:42:06

Just a thought but maybe Brent would share his secrete slipper design with me? I may be pushing it. LOL

If not maybe I can copy one of my modern dirt bike pistons? Nathan or Nich, got any ideas?

Hope I can sleep? Is it Christmas yet?

Jim,
The RSC barrel is not solid and has air passages between the sleeves. I know that sonicrete has stated for years that they were Siamese/solid just like the 1100's but I never bothered to correct him. Anyhow the RSC/AHM barrel I have, are 70mm bore but I see no reason why they cannot be re-sleeved down. This will then give every external indication that it is a 750 other than the cooling holes because that is what is cast into them and the external dimensions are exactly the same.
I tried to email you the zip file with it all but it wouldn't accept it, so I'm going to send the pictures piece meal starting tonight.
As for the pistons, you don't need my piston design as the new cylinder head design doesn't need as much such additional efforts and in fact it would be of no use it because mine are made for the different valve angles. Using my improved version head with the straight ports has the same basic combustion chamber shape I've adopted but is very much less pronounced as this is all you need. This is because the intake charge has much more efficient and effective tumble and will maintain turbulence more effectively than the OEM could ever hope to. Get your piston dome as low as practical and the squish correct and you will be good to go. You will know this when the time comes as the proof will be less total ignition advance (although I don't think you will get it as low as DonR uses ???? (I can't work that one out).

Captain

Posted: Thu May 29, 2014 7:15 am

JJam wrote:

...... I'll get on with pulling the 1000c motor apart and dropping a cylinder out to get the measurements.

I'm OK with 18" wheels but not a fan of how heavy the Comstars are. I am looking into some early 18" GSXR 1000 wheels as they came with a 4.5" rear I believe?

My heads spinning with how much there is to do but I love the challenge!

Jim

Hey Jim, punching out the liners were easy.. I'm sure your oven idea will work.. I read or saw a video about heating the block to 300 degrees and they will fall out?? Use the laser temp gauge to check..

The first gen 1986-1987 GSXR1100 had 2.75" x 18" front and 4" x 18" rear. That's what I have on my CBX. 1988 GSXR1100 rear had 4.5" x 18" rear.

Maybe you can drill a bunch holes in the Comstar hub, to reduce weight???

Posted: Thu May 29, 2014 8:10 am

I figured the new head would be involved soon. This sounds like a destroked 1000/1100 motor like has been kicked around here for some time, but with a head and CC shape that should do nicely with the 12K or more revs.

I might try just a little hotter than 300, I've read something more like 400 for valve guides to fall out, but that's with a lot thicker aluminum than the blocks.

CB1100F Joined: Jun 18, 2006 Posts: 2523 Location: UK

Hi Jim

Sounds like a nice project for Dennis to race with, saw him race at Road America a few years ago, very smooth rider

I have removed liners from 900 & 1100 blocks in the oven when the wife is out, 150 deg C and they fall out, just used a couple of pieces of 5'' timber to stand the block on

Would it be of any strength advantage to use a longer 1100 steering head tube when you have bored the frame out?

Good luck

Keith

Posted: Thu May 29, 2014 10:46 am

I normally wouldn't say this as it doesn't bother me, but for others it may be easier to find and read if this was moved to the "Performance Technical" section.
Building a race bike is very much a performance matter.

Captain

CB1100F Joined: Jun 18, 2006 Posts: 2523 Location: UK

Captain wrote:

I normally wouldn't say this as it doesn't bother me, but for others it may be easier to find and read if this was moved to the "Performance Technical" section.
Building a race bike is very much a performance matter.

Captain

I think Jim is so excited he must have forgot to put it in the Performance Tech section

Keith

Posted: Thu May 29, 2014 2:29 pm

Motocanada wrote:

Dennis

why not run 18 inch radials, splits the difference. Gives you the feedback from 18s you like (I prefer it too) but the modern technology of radials. My R runs these, as did my Laverda RGS1000 before it. Bothe were improved immeasurably.

David

The dunlops I run are modern race compound rubber (medium-soft) on bias ply construction tires. I don't know of a sticky 18" radial tire set...

Posted: Thu May 29, 2014 2:47 pm

I got curious - 29mm carbs have just over 660 square millimeters of throat area each and 35mm would be just over 962 square mm. Hhhhhmmmm......

Posted: Thu May 29, 2014 4:08 pm

Good luck to you both and have fun!
If If i'm corrcet on this, AHRMA has no class for 1100's but I see bikes 10 years newer in there races?

Posted: Thu May 29, 2014 5:26 pm

OK sounds like I need to send Brent some money to ship the cylinder block and get on with resleeving them.

I like the idea of large bore short stroke for faster revs but need to decide which rods will work the best & stay to some sort of a budget plus be strong enough to handle the high revs?

Options are;

1. use 750 rods and polish and peen them. cheapest and weakest.

2. 1100 rods do the same treatment and use a spacer plate to get the deck height. This is a cheap route also but may cause problems with cam chain length??

3. Have some custom Carrillo rods made at the same length as 750 rods with 17mm pins??

Also, I didn't mention it but I will be annieing up for one of Brents heads. This will make all the difference when Dennis is trying to beat the larger cc'd bikes out there.

As far as putting this thread in the performance forum? I don't really care and have never put anything that I do in that forum. I'm not doing anything that I personally came up with so IMO I'm not doing anything special. In other words. I'm a copy cat as I'm way late to the game. About 30yrs so it seems.

Peace, Jim

Posted: Thu May 29, 2014 5:39 pm

JJam wrote:

OK sounds like I need to send Brent some money to ship the cylinder block and get on with resleeving them.

I like the idea of large bore short stroke for faster revs but need to decide which rods will work the best & stay to some sort of a budget plus be strong enough to handle the high revs?

Options are;

1. use 750 rods and polish and peen them. cheapest and weakest.

2. 1100 rods do the same treatment and use a spacer plate to get the deck height. This is a cheap route also but may cause problems with cam chain length??

3. Have some custom Carrillo rods made at the same length as 750 rods with 17mm pins??

Also, I didn't mention it but I will be annieing up for one of Brents heads. This will make all the difference when Dennis is trying to beat the larger cc'd bikes out there.

As far as putting this thread in the performance forum? I don't really care and have never put anything that I do in that forum. I'm not doing anything that I personally came up with so IMO I'm not doing anything special. In other words. I'm a copy cat as I'm way late to the game. About 30yrs so it seems.

Peace, Jim

What is the weakness of the 750 rod? Because its 15mm pin? Could they not be resized for 17mm pins with a thicker cross sectioned pin, or would this remove too much area around the pin? Also note CROWER makes custom rods to any size you want? I know of another member here who had some made for his factory race bike (to replace his 30+yr old titanium rods) .... and I inquired about some a few years back. I think they were like $800 for a set, but that was considering a group buy of maybe 10 or more sets.

Posted: Thu May 29, 2014 5:54 pm

JJam wrote:

OK sounds like I need to send Brent some money to ship the cylinder block and get on with resleeving them.

I like the idea of large bore short stroke for faster revs but need to decide which rods will work the best & stay to some sort of a budget plus be strong enough to handle the high revs?

Options are;

1. use 750 rods and polish and peen them. cheapest and weakest.

2. 1100 rods do the same treatment and use a spacer plate to get the deck height. This is a cheap route also but may cause problems with cam chain length??

3. Have some custom Carrillo rods made at the same length as 750 rods with 17mm pins??

Also, I didn't mention it but I will be annieing up for one of Brents heads. This will make all the difference when Dennis is trying to beat the larger cc'd bikes out there.

As far as putting this thread in the performance forum? I don't really care and have never put anything that I do in that forum. I'm not doing anything that I personally came up with so IMO I'm not doing anything special. In other words. I'm a copy cat as I'm way late to the game. About 30yrs so it seems.

Peace, Jim

What about option #2a? Since custom pistons will be made anyway move the wristpin location up in the new pistons the same distance the 11F rod is longer (there's plenty of room between the ring land and the wristpin hole) and not have any cam chain length issues, won't require a spacer plate and won't have any added cost? (3rd time me mentioning this might be a charm... Smile

)

Posted: Thu May 29, 2014 5:59 pm

pn27416 wrote:

Good luck to you both and have fun!
If If i'm corrcet on this, AHRMA has no class for 1100's but I see bikes 10 years newer in there races?

AHRMA runs modern bikes EXCEPT fours - there are lots of clubs that do that so AHRMA goes after the others. AHRMA also just added a "Next Gen Superbike" class for the vintage 750cc superbikes that started in '83 after the 1025cc class was phased out.

There's no 1100s allowed - 1025cc is the Vintage Superbike limit.