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BIG BORE suggestions??

24K views 62 replies 26 participants last post by  r6rider 
#1 ·
I just bought a 88 TRX 250r. I am new to the two stroke world and have owned a four stroke all my life. I was wandering if some of you experts could give me some big bore suggestions. Some of the things that mean the most to me about this rebuild is the hp (i want 60+), quality engine work, and i still want to be able to run it on C12 or other non alcohol race fuels.
Some of the big bores i was looking into is the ESR pv 330, the ESR pv 350, the ESR pv 370, and a dennis packard big bore.
Any suggestions????????
any feedback would be greatly appreciated
 
#39 ·
How often to you hear about a sparks, duncan, ct, or lrd cylinders fail? About half as much as esr. Pro x cylinders are made way better. You think esr will remember your name or take the time to custom port a cylinder for you? I think not. They are to big to care anymore. If you cant afford to build right the first time then you cant afford to do it twice.
 
#40 ·
I have a new ESR 330 PV in the for sale section comes with a lot of extras. For the money you save on the cylinder you can have someone port it. Check the listing out.


Also,

Carlos and BDT are a recent development here on the forum over the past year or so. He has not always be here. To us here on 250r.net, BDT is a new thing. Not necessarly the case in real life though, im not sure how long BDT has been around.
 
#50 ·
This is another outstanding thread about horsepower and dyno...Christ!

Who gives a Flyin F'

Just nice to see the 'fast guys' staying out of this pissing match..

I am one to have stayed clear of Carlos, but for once, I think we see eye to eye on something....and my .02 I would encourage most to stay clear of a 370 cylinder.
 
#52 · (Edited)
I have never ran a motor from BDT nore do I plane to run on in the future. Now Offence carlos.

When I first bought my esr 350 pv trx 9 port ,pipe, reed, cr ignition, pump gas dome and I already hade a 39 pwk. Tom from ESR told me I should get 68 hp out of it. When I first put that engine to gether I Was kinda a dissipoint ment. I went throw a few piston from lack off piston to cylender wall clearence till esr disided it needed more inorder for them to live. Another big problem I had was the power valve failed twice and the blade fell off in the the engine and dameged two more pistons. So I got a local biulder to make a block off plate for the PV. That was one off the best things I ever did to that engine. I lost vary vary little on the bottom end and gaind hugh on the top end. If you are looking for a dune drag engine I would never biuld a nother PV engine. This was esr old pv. May be the fixed but I would never bould a nother PV engine again.

After I spent two years tuning this engine to how I like it. I got the cylender reported by K&T. I bumped the compretion up to race gas. I got the 39 pwk bored to a 40.5. The best thing that I did to it was blocked the PV of. After the engine rain the way I expected when I bought it from ESR. I had it on a local dyno witch i hard up for number and it made 57 hp. You may not think that was good but it had a hughly broad power band. It made 54 -57 hp over 1200 rpm. If you take this set up and ported it more and put a trx 11 pipe on it would be even faster in a drag race, but I biult the engine to my likings.

Dont be stuck on a number from I dyno my local dyno guy always says "I would rather have a 40 hp engine and be beting a 50hp engine all day long." Dynos just give number and are tools to tune from nothing more.

Even after all that hasle I would buy a nother ESR engine. But make sure you run extra piston to cylender wall clearence. Dont get a PV there a wast off money and the fail. I now your on a buget but if you going to do a straker dont cheap out on the crank because it could cost you every thing in the end. (cylender, crank, cases) Stay far far away from wisco cranks, Use hot rod or OEM cranks.

If I were you I would pick ether a 310-330-350 non PV on race gase with a pipe. Good stock strock crank OEM or hot rod. With a 39 or bigger carb. Ruin ESR porting for now and when you want more send the cylender to builder off chose and get it ported. This is wought I have learned from expereance. I hope you dont have the same problems I did.
 
#53 ·
Even after all that hasle I would buy a nother ESR engine. But make sure you run extra piston to cylender wall clearence.
This mistake can be bypassed with a good bore. No need for extra clearance. The best power for the money is to get an ESR cylinder without porting, without bore and a blank dome. Send that to a good builder and you will not have any problems. My builder, Pete at Hybrid has done several of these and all customers have no complaints what so ever. With a good port, bore and precise compression ratio you cannot go wrong. You will get exactly what you want and not have to worry about the economical ESR bore. You get awesome power and no seizing.
 
#54 ·
I find this whole thread and many others others amusing. Dyno this, dyno that, make some baseline runs, get out there line the Fuck up with some other internet racers and see how your dyno racing pans out. That's how you know the tolerance the given dyno you tune on compares. Apparently I run the junk. :)
 
#57 ·
To me it doesn't matter what everyone says if I want a certain bbk ill buy it if it fails its my fault. I've heard good and I've heard bad about hotrod cranks but I have one in my kx500 and its still in tact I had one in a blaster years ago no problems. I recently bought a +4 hotrod crank for my 250r. My point is buy whatever you want and can afford its your bike its what makes you happy. I'm buying a esr310 tomorrow and will be sending it to Carlos for porting. I've done a good bit of business with him lately and asked a lot of advice from him and he has answered every question.
 
#58 ·
Percent wise is what I am getting at. Obviously there will be more to fail in sheer number. But with the number sold to numbers failed will be close in percentage. lets make this easy. ESR sells 100,000 and 25,000 fail. That is 25% of them failing. LED sells 100 and 25 of them fail. That is also 25% of them failing. So I am right and hope this helps you to understand. From one Idiot to another.
 
#60 ·
#62 ·
Everyone has an opinion and the right to express it, when you offer information as I tend to do, you open yourself to scrutiny & criticism...every word can be challenged and disputed; goes with the territory.

This forum is the best informed, has the largest knowledge base of any other 250R forum that I have seen. 99% of everyone here are 250R enthusiast that appreciate the help and information members provide each other.

Honestly; I am proud to be part of TRX250R.NET with everyone else on here. I have seen a significant increase in understanding, accurate information given, and a willingness to help each other out that you will not find anywhere else.

Just check out all the other forums and you will see the quality of this group is unmatched...

Carlos.
 
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