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Thread: Race chassis

  1. #1351
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    I only raced the EX a time or two in 250SB, but small bikes like that are fun to ride on the track. A friend is having good times with his EX300.

    The intent had been to eventually build a frame with 125GP wheels etc but the trick downdraft-intake head got stalled with my engine tuner (as did so many projects) and the window of opportunity closed on the project.

    http://www.eurospares.com/ex2501.html

    With CR carbs and race exhaust on the otherwise stock (and well-used) engine the bike was competitive in a drag race against a nicely ported/pistoned 250Prod EX (with my local club production meant any internal mods as long as you stay in the displacement limits, stock intake and exhaust -- that makes it a lot easier to police).

  2. #1352
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    25th March 2004 - 17:22
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    Quote Originally Posted by Grumph View Post
    Bear in mind Dave that CAMS down here has a 150/2T 250/4T class. Given that the 250 production Kawasakis are now obsolete by virtue of the 300's being adopted....I hope Michael's pics inspire someone.
    Ah 16's....My GPZ500 F3 bike went onto 17's when it was transformed from a road bike. But it was raced for most of a season on 16's - Dunlop 591R's.
    Not bad - but if you hit 7000 while cranked over, it went sideways....I'd got quite a lot more HP out of it while keeping stock cams/carbs but it was all up top.
    When it was done properly with big cams and flatslides, it was actually much more pleasant to ride.
    Bear in mind Greg, i find it hard to get very excited about any four stroke, but the project was cool enough, just needed a smaller lighter more powerful engine.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
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  3. #1353
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    Dave, the Dymags I originally bought for the EX250 project are sitting next to a 2015 KTM 250SX engine, hopefully that will get everyone's approval. The wheels, brakes, powerplant etc have yet to reach critical mass and implode into a rideable bike.

    cheers,
    Michael

  4. #1354
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    Quote Originally Posted by F5 Dave View Post
    Bear in mind Greg, i find it hard to get very excited about any four stroke, but the project was cool enough, just needed a smaller lighter more powerful engine.
    Oh understood...And my F3 500 was about the same weight but 72hp at the wheel. The blown version was about 20kg heavier but had over 100hp at the wheel...

    When I get access to my camera again, I'll post some pics of a 500 head lurking under the bench and dating from about '88 which will make Michael laugh....
    Reason is a tool - remember where you left it..... The late, great, John Clarke

  5. #1355
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    That's pretty handy for one of those. Wonder what TonyMcMu was getting from his?
    I dynod Spargo's ZXR400 and it was nowhere near that on Ave but he'd had to give back the pipe which I think Tony had used on his 400. Or something.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
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  6. #1356
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    Quote Originally Posted by F5 Dave View Post
    That's pretty handy for one of those. Wonder what TonyMcMu was getting from his?
    I dynod Spargo's ZXR400 and it was nowhere near that on Ave but he'd had to give back the pipe which I think Tony had used on his 400. Or something.
    I did the top end on tony's 500 - someone at Boyles set the bottom end up for him. When asked Tony admitted to "over 80" - but added it depended on the nitro percentage, LOL. My original 500 was on the Meth/Toluene that I set Tony up with to start. The blown one was on straight Meth.
    I also did the first 400 head for Tony - all the ones he did after that were copies of mine.
    Reason is a tool - remember where you left it..... The late, great, John Clarke

  7. #1357
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    i have Spargo's sister bike , i got 67hp from it from a dyno jet 150 when i bought it, had the f3 race kit on it , i did get 74hp in the end
    i'm over buckets

  8. #1358
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    Yeah think it was like 65 if that but old pipe jammed on not setup ready to sell. Have it on pc backup somewhere
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  9. #1359
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    That said probably on meth jetting before and just a guess.

    Talking of meth, while we are clearly in the chassis thread. .
    I remember the virulent Taylor letters to the editor of KR re the Dallas BMS Dookati vs TZ250 for F2. That bit somewhat.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  10. #1360
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    Quote Originally Posted by F5 Dave View Post
    That said probably on meth jetting before and just a guess.

    Talking of meth, while we are clearly in the chassis thread. .
    I remember the virulent Taylor letters to the editor of KR re the Dallas BMS Dookati vs TZ250 for F2. That bit somewhat.
    i still have those mags



    Kinky is using a feather. Perverted is using the whole chicken

  11. #1361
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    Quote Originally Posted by F5 Dave View Post
    That said probably on meth jetting before and just a guess.

    Talking of meth, while we are clearly in the chassis thread. .
    I remember the virulent Taylor letters to the editor of KR re the Dallas BMS Dookati vs TZ250 for F2. That bit somewhat.
    when i got mine it still had meth pilot jets in it , would not idel under 11000 lol . was not until we put in (murphy diesel )lol grinds on the cams it went real well
    i'm over buckets

  12. #1362
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    Quote Originally Posted by F5 Dave View Post
    That said probably on meth jetting before and just a guess.

    Talking of meth, while we are clearly in the chassis thread. .
    I remember the virulent Taylor letters to the editor of KR re the Dallas BMS Dookati vs TZ250 for F2. That bit somewhat.
    I don't know to this day exactly who pushed for 2V 750's for F2 - but in the end even on Meth they were actually pretty evenly matched on most NZ circuits.

    But that shitfight certainly helped lead to the banning of meth - which had far too many unintended consequences IMO. The balance of engine types in F3 immediately went haywire. Engine development costs went through the roof when we all tried to get HP on petrol which had been easy on meth blends.
    Reason is a tool - remember where you left it..... The late, great, John Clarke

  13. #1363
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    As promised for Michael to add to his collection of Kawasaki twin oddities....
    This head was done about '88. The aim was to equal Tony's nitro motor but on straight Meth. It had already dropped a valve so there was plenty of welding incl a couple of new inserts. Valves were I think 2mm bigger inlet and 1-1.5mm bigger exhaust. Honda single valves straight off the shelf. Cams as per usual - the biggest Megacycle grind...R&D springs - which broke regularly. Pair of 40mm Dellortos. Inlets lifted as high as possible. Exhausts had considerable work too.
    The comparo pic is against a '16-'17 L2 GSXR1000. We weren't far away, LOL. Memory says we used more valve lift in the Kawa than the kit cams in the GSXR - and spun it to 13k vs 14 for the Suzuki.
    We probably did achieve the 80hp we wanted - but not for long. Insert dropped out as is visible.

    Never been able to throw it out....
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    Reason is a tool - remember where you left it..... The late, great, John Clarke

  14. #1364
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    Thanks Greg, it looks similar to the downdraft intakes on the 250



    Once you do that you get to deal with "are the carbs too tilted to work properly?" and "how do I squeeze everything back into the frame/under the tank?" That last was an incentive for my Laverda frame. After developing the engine on the dyno the intake tracts were too long to fit into the stock frame, and on the new frame (Mk 5 version) I had the back of the tank hollow for the bellmouths to not be obstructed:


  15. #1365
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    Quote Originally Posted by Michael Moore View Post
    Thanks Greg, it looks similar to the downdraft intakes on the 250



    Once you do that you get to deal with "are the carbs too tilted to work properly?" and "how do I squeeze everything back into the frame/under the tank?" That last was an incentive for my Laverda frame. After developing the engine on the dyno the intake tracts were too long to fit into the stock frame, and on the new frame (Mk 5 version) I had the back of the tank hollow for the bellmouths to not be obstructed:

    Yes, same idea as the 250. The angle is why Dellortos rather than our usual RS Mikunis.

    To get back to chassis related topic - looking at your SF, you can see the attraction of an Ogier Laverda style tank in the rear subframe as it then leaves room for the carbs - and a possible airbox - in the usual tank position. But as usual a major component would need to be relocated - the pipe.
    We didn't have space problems. This version of the EX went into the frame used for the blown one - a GSXR750J. Plenty of room under the std Suzuki tank.
    No pics of that bike exist either blown or not. Built in a tearing hurry, tested in haste, developed at a frenzied pace - you get the idea, LOL
    That rolling chassis was written off at the opening meeting of the extended Ruapuna circuit here. Owner had loaned it to a sponsor who'd stuffed an 1100 engine into it with RS carbs etc...throttle stuck open. Rider locked up the front and went down, rolled away OK. Bike stood up and accelerated...hit a pile of dirt and launched like an Exocet missile over the boundary fence. Couple of bounces later it finished up in a tree...very broken.
    Reason is a tool - remember where you left it..... The late, great, John Clarke

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