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machwon
11-11-2007, 05:58 PM
Here is a run from a trx250R with a +4mm hot rods stroker crank. The cylinder was an 87 bored .060 over which makes it 272 cc's. Other details were boyseen rad valve, FTZ pipe, 40.5mm keihin carb 58 pilot, DGH middle, 185 main, cool head.

criminalpoet
11-17-2007, 12:27 PM
Respectable numbers for a pretty much stock bore bike!

machwon
11-18-2007, 12:34 PM
Thanks, I thought it would do a little better than this, but its still really good. We got it upto 52.7 hp last week, hopefully I can find some more!

headache
12-19-2007, 12:20 PM
what type of porting does the motor have? Was it ported for the stroker crank? if not then your definetly not getting the full potential out of that motor.

machwon
12-20-2007, 07:09 PM
The motor has what I consider a full top end port job and it was cut specifically for the 4mm lr stroke. There's not much more to do other than make it a full out drag port. I would be interested to see any info you have on a stock cylinder motor pulling mid or high 50's without using alky or oxygenated fuel.

criminalpoet
12-21-2007, 03:59 PM
I have an 89 stock long rod motor with the stock cylinder still on it, 1 Dir Racing built it and it pulled 52hp with 32ftlbs of torque with their MX/Dune porting. I have recently sent it back to them for their pre-pusher design and this time around I am adding a timing advance plate. Im told to expect 60hp with somewhere around 35-38ftlbs of torque. They also offer a custom inhouse pipe for their pre-pusher engine design which is supposed to increase the power by another 15-20%.

Im not sure if they offer their pre-pusher design to the public or not though, ive been a customer of theirs for over 10 years now. But those guys have been building race bikes for over 30 years and theres always little trick here and there to add hp. You should see how they modify their pistons too, its pretty wild. Attention to detail, thats why I like them, and with an inhouse flow bench and inhouse dyno they are able to check for things and do the type of testing on your motor before sending it out that most other shops cannot do.

No matter what though those are very respectable numbers! Most builders/shops out there are not getting their customers over 50hp on a stock cylinder.

machwon
12-24-2007, 08:00 AM
Criminalpoet, are those rear wheel dyno numbers or from the countershaft? Do they have a website with there info? I would be interested in seeing any of the stuff they have.

Not that I'm doubting what you say, but I don't think I've seen but one or two dyno runs that just hit 60, and I'm pretty sure they had it on alky. You are right about hitting 50 hp as well. There's not many who get that high either. I got my hands on a 38mm alky carb, so I'm going to hopefully try it soon.

08 GPX 177 ATC
04-18-2008, 08:00 AM
I would like to get my 250R atc dynoed.

Buttermilk
05-01-2008, 08:12 AM
http://www.exriders.com/vbb/showthread.php?s=&threadid=349083

The link is to my own 250R with a +4mm crank. It's taken me about one and a half years to get it to where it's at now.

Regards,

Rog

machwon
05-07-2008, 07:22 PM
Buttermilk, those are awesome numbers for a stock cylinder. Keep up the good work!

genoapb
09-30-2009, 07:35 PM
Any updates on this cylinder yet? You should do a comparison from gas to alky once your happy with the power on gas!

machwon
10-01-2009, 05:26 PM
Originally posted by genoapb
Any updates on this cylinder yet? You should do a comparison from gas to alky once your happy with the power on gas!

Hello Genoapb, I had a loaner alky carb but it was too lean and just revved to the moon. I also tried a 44mm lectron on gas but it did worse than the 40.5mm, even on a 363cc motor I did it wasn't quite as good. I ended up selling that cylinder, then did a 310 that went 58 to the rear wheels and sold that one too. Right now I just have my 4mm bottom end but I plan on doing another stock cylinder soon. I still don't have any alky carb, got one I try? Do you still have that awesome stock cylinder banshee?

buford
10-12-2009, 10:19 AM
Hey buttermilk, I have a question for you, looks like you beat on this 4 mil for 1.5 -2 years on the dyno and I assume on the track. My questions is the reliability of the hot rods 4 mil stroke crank. Did you do anything like rebuild the crank and put a new rod on it every year or did you do anything at all?

I broke a esr 4 mil stock honda rod crank (broke the rod in 2) on a 69 mm 4 mil motor I had when I missed a shift and it reved to the moon. I am worried that these hot rods cranks aren't any better.

I haven't heard too many problems other than maybe not being completely true, other than that, not much.

what are your thoughts? I get scared with the rod/stroke ratio of these cranks when building a motor with some port timings. Mine was 192 on the exhaust, a bit less than the one you built.

genoapb
10-12-2009, 10:21 PM
machwon, ive been wanting to make it to your shop for quite some time now and have alot of parts you could try out. I need to get 3 bikes on the dyno. One of them being that stock cylinder banshee, I keep thinking with a little dyno tuning we could put it in the 3's! Hopefully I can make it down there over the winter. Are planning on going to that Ionia race this weekend? I dont check this site that often, are you a member over at atvdragracers? I check that site quite often.