Motorcycle Modified Class Questions

[Chaulkdust]

My name is Ron Pavlak from West Bloomfield MI and Homosassa Fl. Being retired I bounce back and forth trying to avoid the snow. I am working on a project to bring to the salt flats in 2008. I have read the rule book several times and have gained a lot of great tips/information from the site. Also, appreciate Jon's hard work and have remitted a check. I have a project 1965 CB160 Honda that I saved from the junk yard and I'm in the process of setting it up to bring in 2008, to run in the 175cc class. I've been into restoring old Honda for many years, but I am new to racing. Thought it best to go slow, as I don't bounce well anymore.

The bike will use a small Turbocharger, since I can't use the stock exhaust system I guess I'll need to run in the Modified Class/BG. I'd like to stay in the Modified Class and not be considered Partial Streaming or Altered. I do not have any fairings on the bike. Just wonder if mounting the Turbo in front of the engine rather than behind it would cause any Class problems (streamlining)? I don't see how it would, but after reading all the posts about rule interpretation/changes I'm just getting paranoid. Also, I plan on using a cafe seat with the little hump on the rear, hopefully this would be OK as well? Does the seat height rule of 36" apply to the seat surface or the top of the hump (highest point on the seat)? I plan on boring out the motor to 175cc's from the stock 160cc's, but I believe this is OK and that you can bore .020 inches over your class limit if needed/desired.

Frame is stock and the motor does go with the frame, didn't plan on a rear fender, and have replaced the stock rims with aluminum rims. Got the info from the site on Riding Leathers/Helmet/Chain Guard/Kill Switch/
Toggle Switch/joining SCTA/BIN/getting a number/damper etc..

Any tips for running small displacement bikes on the salt? I thought light would be best, narrow tires, and blast the tiddler down the flats.

That's probably more than enough for now.

Ron

[Stainless1]

Welcome and good luck
max tail section hight 36 with rider on bike.
Stock cases can be bored to class limit,
turbo is not considered streamlining or fairing, it is part of the motor
Any front fender you choose or not
Same with rear
Pay attention to number plate mounting rules, must be in front of axle.

To go fast with small motor it helps if you are really small....
Practice on getting small....
have fun, go fast, be safe

[bak189]

I just hope the  "new"  minimum
speed limit will  allow the small displacement
bikes to compete within the SCTA/BNI..........if not bring it to the BUB M/C meet in Sept of 2008.....

[sockjohn]

My name is Ron Pavlak from West Bloomfield MI and Homosassa Fl. Being retired I bounce back and forth trying to avoid the snow. I am working on a project to bring to the salt flats in 2008. I have read the rule book several times and have gained a lot of great tips/information from the site. Also, appreciate Jon's hard work and have remitted a check. I have a project 1965 CB160 Honda that I saved from the junk yard and I'm in the process of setting it up to bring in 2008, to run in the 175cc class. I've been into restoring old Honda for many years, but I am new to racing. Thought it best to go slow, as I don't bounce well anymore.

The bike will use a small Turbocharger, since I can't use the stock exhaust system I guess I'll need to run in the Modified Class/BG. I'd like to stay in the Modified Class and not be considered Partial Streaming or Altered. I do not have any fairings on the bike. Just wonder if mounting the Turbo in front of the engine rather than behind it would cause any Class problems (streamlining)? I don't see how it would, but after reading all the posts about rule interpretation/changes I'm just getting paranoid. Also, I plan on using a cafe seat with the little hump on the rear, hopefully this would be OK as well? Does the seat height rule of 36" apply to the seat surface or the top of the hump (highest point on the seat)? I plan on boring out the motor to 175cc's from the stock 160cc's, but I believe this is OK and that you can bore .020 inches over your class limit if needed/desired.

Frame is stock and the motor does go with the frame, didn't plan on a rear fender, and have replaced the stock rims with aluminum rims. Got the info from the site on Riding Leathers/Helmet/Chain Guard/Kill Switch/
Toggle Switch/joining SCTA/BIN/getting a number/damper etc..

Any tips for running small displacement bikes on the salt? I thought light would be best, narrow tires, and blast the tiddler down the flats.

That's probably more than enough for now.

Ron

Big thumbs up for going to run such a cool old bike, and especially for going turbo on such a small motor.  Not an easy feat.

125cc moto GP tires are pretty common on small bikes from what I have seen, but there are other options as well.

[frogpirate]

Hi Ron, I am a newbie here as well. I am also looking at doing a turbo-charged relativly small (500-600cc) bike. I'd be interested in talkkng with you about which turbo your going to use etc.

Also, out here (PNW) there is a very large CB-160 racing community that road races at Portland International Raceway and Seattle International Raceway (which is now Pacific Speedway I think). These guys are pretty good at tuning etc. and Joe has a pretty good stash of parts: www.viciouscyclepdx.com

Good luck, sounds like a fun project!

Ken

[sockjohn]

Hi Ron, I am a newbie here as well. I am also looking at doing a turbo-charged relativly small (500-600cc) bike. I'd be interested in talkkng with you about which turbo your going to use etc.

Also, out here (PNW) there is a very large CB-160 racing community that road races at Portland International Raceway and Seattle International Raceway (which is now Pacific Speedway I think). These guys are pretty good at tuning etc. and Joe has a pretty good stash of parts: www.viciouscyclepdx.com

Good luck, sounds like a fun project!

Ken

Garrett GT-12 or GT-15 perhaps?

[Chaulkdust]

Yes, I saw the thread on the speed limit idea, I believe it was 70mph min. Hopefully, I’ll be able to go faster than that – maybe 85? BUB would work as well assuming they get all the other issues worked out regarding staging to run. I’ve ended up going with a IHI RHB32 Turbo for the project. It’s about the size of a dollar bill and weighs 6 pounds or so.  Spent a lot of time learning about turbo’s, compressor maps, AR ratio’s, intercoolers and lot’s of sizing calculations. Very interesting material, hopefully I’ll be able to put it to good use.

Anyone know of a really small water to air intercooler for a turbo? Most things end up being too expensive or too larger. May not even need an intercooler if I can’t generate enough boost, will have to see how it works out.


Ron

[Sumner]

Yes, I saw the thread on the speed limit idea, I believe it was 70mph min. Hopefully, I’ll be able to go faster than that – maybe 85? BUB would work as well assuming they get all the other issues worked out regarding staging to run. I’ve ended up going with a IHI RHB32 Turbo for the project. It’s about the size of a dollar bill and weighs 6 pounds or so.  Spent a lot of time learning about turbo’s, compressor maps, AR ratio’s, intercoolers and lot’s of sizing calculations. Very interesting material, hopefully I’ll be able to put it to good use.

Anyone know of a really small water to air intercooler for a turbo? Most things end up being too expensive or too larger. May not even need an intercooler if I can’t generate enough boost, will have to see how it works out.


Ron

Ron I have two IHI RHB5 turbos and haven't been able to find any compressor maps for them.  Have you found IHI maps???

   

Good luck with your project, I sold and road a number of those Honda's.  Neat bike,

Sum

[Seldom Seen Slim]

Chalkdust/Ron:

Here's a photo of Nancy's EX250 motor -- and if you look in the center (I know, it's really busy in there) you'll see the intercooler Mike fabbed up.  For reference you can see the Land Speed oval ID tag -- which silvery oval is about 3" long.  The intercooler is tiny -- so icewater-to-air, not just water/air, is what we run.  If I can find another photo I'll send it along (if you want me to do so).

The stainless braided line that's hanging down takes the icewater from (what used to be) the gas tank and feeds it to the top of the intercooler.

[Chaulkdust]

Sum - here is a link to the RHB5 Compressor Map.

http://www.mx6.com/forums/1g-faq-submission-area/140946-ihi-rhb5-vj11-compressor-map-psi-plots.html

Ron

[Chaulkdust]

Jon, that's absolutely BEATUIFULL! Do you think Mike would make me one for a reasonable charge? I also thought of putting in an Aux gas tank and using the main tank for cooling if I went the intercooler route. Is that the bike that currently holds the MPS-BG record in the 250cc class? If you don't mind me asking, what type of pump did you use for the cooling system? Do you run the turbo oiling from the engine or do you utilize an external system? I have to use an external system on mine for a variety of reasons.

Ron

[Sumner]

Sum - here is a link to the RHB5 Compressor Map.

http://www.mx6.com/forums/1g-faq-submission-area/140946-ihi-rhb5-vj11-compressor-map-psi-plots.html

Ron

Thanks, you can't imagine how much time I've spent looking for those.

Now find one for a Garrett GTP38 and you will make GH (and me) very happy,

Sum

[firemanjim]

Ron,I have gotten both an air-air and water-air made by Bell Intercoolers and they are great to work with,got the water pump from them also.
Good luck with the project,going blow-through?
You could scavenge all the bits from a Yamaha Turbo Seca, I did this on my son's last set-up. Worked very well. IIRC it is an IHI RB3?? Carbs already set-up for boots,fuel pump and pressure regulator,etc. Still using the carbs on current 600 turbo set-up.

[Chaulkdust]

Sum I have the GTP38 map, but it is in Excell, I can post it or send it. Send me an e-mail and I'll attach it for you.

Ron

[RZ350]

Jon, have you ever dyno'd that 250?

I'm curious what kind of power it makes.

I'm curious about many things, but power is always on the top of my list!!