new to 2 strokes - need advice

[DirtTrack]

Here's the scoop, I bought a trike, and need some advice on jetting the carb, here's the specs:


1984 Honda 250r
bored .080 over
wiseco piston
boyeson rad valve / reeds
dg exhaust
stock carb, 50 slow jet, 130 main jet, needle on 1 lean from stock
running Castol at 32:1

Trike idles great, has tons of go in 1st gear, seems to lose some power in higher gears.

I'm thinking it's running rich, thus the loss of power in higher gears, however, the slow and main jets are at stock, even though the machine is modded.

Shouldn't I have to richen it up when the bike has mods such as this?

What would you recommend?

Thanks,

Brian

[Lots_Of_Nothing]

rich???????? nooooo, you are running LEAN, for one, you got all those mods with a 130 main jet????? THATS STOCK JET SIZE....go at least to a 150 main jet......

[smokinwrench]

I am no expert but wherre you live has alot to due with your jetting. Altitude has lots to due with it if you live next to the ocean at sea level or up by Denver at 5000 ft. The best thing to due is read your spark plug and decided if its running rich or lean and go from there. If the plug is black your running to rich, wich means you nead to lean it out. I'm not sure anyone can guess what jets you need to start out with.

Good Luck
Josh

[Lots_Of_Nothing]

i can guess very very positively, start with 150, i had the same exact problem......once you get a bigger jet in there your gonna feel the difference and trailprotrailpro gonna love it

[TimSr]

Im with Smokinwrench. Start with what youve got and take some plug readings. Nobody can even remotely guess what size jets you need, especially if you dont know how well the stock jetting worked before the mods. First off, stock jetting tends to be rich for the simple sake of erroring on the side of rich. Fiber reeds tend to make it run richer than stock metal ones. Contrary to popular belief, a different pipe does not mean it will run leaner. It may run leaner OR richer, or about half the time, make little carburation difference at all. A fresh bore appears to run leaner, while a worn out bore appears to run richer, but a jet change for a normal overbore because of the capacity change isnt very likely. There is a good change your 130 jet may be appropriate, but I can flip a coin and be as accurate as anybody elses guess on a message board. You need to do some test runs and take some plug readings to see which way it needs to go, if any, or if youd prefer you can take somebody's wild guess and be prepared to deal with the consequences if that guess is wrong, but I wouldnt advise it.

[Lots_Of_Nothing]

my guess is not "wild" its right

[TimSr]

Two identical bikes, off the showroom floor, going to the same household, and being ridden by the same rider at the same place often require different carburetion settings for optimum performance. While I believe you are confident in your opinion, I sincerely believe that even Houdini would have difficult time naming off a correct jet size from a message board, without even looking at a spark plug.

[DirtTrack]

Ok, some more information:

I live in SE Wisconsin, about 700-1200 ft above sea level.

The bore job is brand new, the motor only has about 8-10 hours on it since it was done, still in break-in phase, which is a big reason I want to get the jetting right before I screw the motor up.

To do a plug check, it would be much the same as with a 4-stroke, correct? Wind it up and kill it out of gear, then pull the plug?

Brian

[TimSr]

Exactly. You want the throttle slide wide open, under load, long enough to get a full throttle reading to setup your main jet. AFTER the main is setup, you do the same tests at half throttle to setup your needle/clip.

[DirtTrack]

Also, in general, is the 84 250r a good machine?

A lot of people seem to prefer the water-cooled trikes, but is there a major difference in reliability, handling, or performance between the 83/84 and 85/86?

Thanks,

Brian

[TimSr]

They are very good reliable rides, with a tried and true motor that has little techincal differnce from all the other air cooled two strokes that have been out there running for years. The lower temp liquid cooled motor top ends will last longer, and in theory a cooler engine delivers more power, but in reality, most people wouldnt notice the difference in the same motor being liquid or air cooled. Most of the improved performance benefits of the liquid cooled R's dont come so much from the liquid cooling, but from other improvements in the newer motors.

[hondaATCman]

Here's a site I think you should check out:

http://www.yellowdogracing.com/techstuff.htm

Hope that helps,

[smokinwrench]

What little I read tonight that website seems to be great. Who created that site? I'm not sure how it is done, but it should be a link on this site to help out alot of people with everything. This site has some good advise on all the basic stuff. http://www.yellowdogracing.com/techstuff.htm What a good find hondaATCman.

Damn I learn something new everyday ;)
Josh

[yater]

wasn't Houdini into dissapearing?j/k