I have a 1986 Honda TRX250R, I sold my Raptor because I wanted a fast honda, now I need help. I picked up the '86 cheap, but didn't know about the short rod vs. long rod question. Recently, I have been looking at the EXR 310's, but they "only" put out around 45-50 hp, would the 330 kit be worth changing rods or machining the cases. Also if I already have the bottom end apart, would it be worth it to build a 350R. Any ideas? I am wanting to be able to run with slightly built banshees, raptors and DS650s (pipes, carbs, heads, mild porting). Mostly all I do is mild trail riding and unorganized drag racing. Also, how much HP can a stock 250 tranny hold up to? I was recently told that some of the ESR 370s are running around 70 hp and stock trannys!
Nic

 

I think that even if you don't go with a 310 or larger you still need to split the cases to make sure everything is in proper working order. Before adding hp you need to make sure you have a strong bottom end. If you are want to do a 310, and you have the cases split, I would strongly recommend going as large as you can go. If you have GOOD port work, you can run with the bikes listed. I have had experience with LRD, ESR, and MP Racing. My stock cylindered bike (done by MP) ran circles around my LRD 300 Niks with LRD sleeve. Not to bash LRD, they make great mx motors but it just didnt cut it for me in the sand. I actually picked it up from MP today. Can't wait to feel the power.

To sum it up. You need to go through the bottom end before you put on a new top end. While you cases are apart, machine them. Run something as big as you want.

 

Thanks for replying. I am really thinking about going through the bottom end of the 250, and eventually making it a 330-350. Hopefully these would have the power I'm looking for. What is the average cost to go through the bottom end with new bearings, seals, and gaskets. I think ESR is around $500 to split the cases and check everything, plus rebuild/balance the crank with a long rod, and machine the cases for the bigger bores. Then again, I could just buy something bigger like a DS or Quadzilla[img]i/expressions/face-icon-small-smile.gif[/img]
Nic

 

Hey, my lil Bro is in the process of shipping his extra engine off to either ESR or CT, for the 330 kit.... I was told by both builders that the HP would be at around 53....... The $$ would be at around 1500-2000.......... For a lil more money you could always go 350 Power Valve............. Both Guys said that the reliability of the 330 is quite long and so forth......................... He is probably going with CT Racing, however, be ready to be without your motor for about 3 months..... But what the he11, it is about winter anyway, so it is going to be too cold to ride, but if you send it off now you will have it back just in time to be ready for the spring riding!!!!! WITH A BRAND NEW BAD A$$ Motor!!

 

I am not really interested in being without my engine for that long. I may just have a somewhat local performance shop do the bottom end and do the top end myself. I am really confident that my bottom end is in good shape, however, I would like to have the better long rod and know for sure. Really the only thing I need is the cases machined, which involves taking the bottom end apart anyway. I have heard of people grinding the cases without taking apart the bottom end, Does anybody know if it would be possible to clean up the areas needing to be machined without stripping out all the gears and such. If it is possible to grind the cases without taking everything apart, maybe that would be the way to go. Then again those extra metal shavings floating around in the gears could hurt later on down the road.

Also, does anyone know the estimated power output of a non-powervalve 330-350R. I am thinking in the 55-60 range, but don't really know for sure. I would be running a ported(TRX 9) ESR cylinder, with a billet head, ESR pipe(TRX 5), and a 38-39 mm carb.
Thanks,
Nic

 

The 330 non-power valve puts out an estimated 53-55 horse power... I was speaking to Da Man at CT, and for the application we were looking for, 53 would have been the optimal, we were looking for the TORQUE for the MX track..... My brother loves the idea of being able to ride the track mostly in one gear!! LOL...... he came from a CR-125 where he had to constantly shift and clutch in order to keep er on da ol pipe!! For him da 330 is da way to go!!
HOWEVER, Da Man at CT Racing did state he could get much more H.P. out of the motor, like 60-70 at the expenst of torque, I guess he meatn taking more off the top of the ports..............????//////// I presume this gives more HP but takes away from torque, i.e. a drag race motor............... aka hill shooter......... Just my .02/worth

 

Dont forget that ESR has a 330 bolt on kit. That's what I put on my wife's wheeler. It did already have the long rod hotrod crank in it. The TRX9 porting has lots of bottom end grunt, even with the TRX-11 pipe that my wife's has. With the pipe your talking about you wouldnt have any problems with low end. I re-ported my wife's cylinder to my specs and it now has still plenty of bottom end and a screaming top end. The bike will run 4.9's in 300ft on a stock swingarm (lowered). It runs right with my ported banshee. It ran a 5.09 with the porting that ESR done to it. The only thing I can say about the bolt on kit is that you get one overbore only, and the piston has to be replaced about every 40 hours. It would really be better to split the cases and have it done right the first time. Any way you go I believe you wont be disappointed. I definitely wouldnt ever go back to the 310 kit. The bigger motors just make more useable power.

 

I would tend to stay away from getting your cases machined with everything still in them. I have never heard of that anyways. Even if it is possible, I think it would br fairly problematic and would want to stay away from it. I think that whatever top end you slap on will give you some more power. I have had some run-ins with bikes from some "generic" companies. Although they have much more displacement, I can still take them. So if you ever get beat by a stock cylindered bike do not be suprised. They make great stuff for great prices, so you get a hell of a deal. Good luck with your decision, and let us know what you decide.

 

esr wont have your motor for 3 months. They are pretty quick with turning around motors.

Dont try and cut your crankcase with the engine together. Your asking for trouble. The crankcase and the tranny are seperate so there is no way for metal shavings to get in your tranny. BUT they will get in your bore and destroy your top end, bearings, and seals. If your going to trench and open up the cases you might as well go all out and do your 350, if you do the crank you might as well stroke it and do your 370.

 

i have a 350pv for sale from CT. one season old and had the bottom rebuilt also. hit me up if interested