Looking for suggestions on a poorly running 1984 250R

[Blown 331]

Well I picked up an 84 250R last Sunday. So far I've changed the fork boots to blue and installed some 18 inch turf tamers that I had laying around that were already on 84 R wheels.
Now I'm not too familiar with the air cooled models but I don't think its running quite right. It doesn't seem like it's opening up quite right, I can't really fell any noticable power band. At first it was smoking really bad and felt like it was flooding out. I drained the gas that was in it and it looked really rich on the oil. I put some of the gas I had mixed up for my 85 R in and it ran a little better with not near as much smoke. I took the carb apart and everything looked great. The bike is bone stock, stock exhaust, air box lid on etc. Has a new UNI filter. I tried to put on the stock carb from my liquid cooled R but it was no where close to fitting in the boots so I stuck with the stock carb. The stock carb has a 130 main jet which souded about right to me. I compared it to a 150 just to make sure someone hadn't drilled the 130 out, doesnt look like it. I lowered the float level a bit. It runs better now. It almost opens up into a nice power band but still sounds flooding but I don't think it is. I turned the gas off while I was riding to see if it ran better right before it ran out, nope. Ran like crap then started reving up, no good running in between at all. So I don't think its actually flooding just kinda runs like it though.
Like I said I'm not too familiar with the air cooled bikes but I'm pretty sure it should run better than this. With the 18s on back it will pull the front wheel in 3rd with just throttle but it still does not seem right. I'm pretty sure my stock 350X with just a slip on exhaust will walk all over it. Based on the condition of the rest of the bike it may have the stock piston. I want to check that soon but would a loose piston make it not have a noticable power band? It also seems to have somewhat poor throttle response at times.

[Jason Hall]

I would suggest you put in a new plug, and make sure the reeds are not hanging open.

[Blown 331]

I would suggest you put in a new plug, and make sure the reeds are not hanging open.

Wow, a new plug. You would have thought that would have been the first thing I would have checked! :crazy: Wow, thats bad. Ha ha. I'll try that out and thanks for the suggestion on the reeds. I bet that's it. I never even thought of that and I did start it with the air box lid out to see how the response was with more air and there did see to be some very light gas misting out the back of the carb, I forgot about that. Very minor though.
What do I need to do to fix that? Just replace them? I have the stock ones out of my 85 R that I replaced with Boyesen, any idea if the are the same? I will give it a shot. Thanks a lot. I'm pretty confident reeds and a plug will do it. Pretty simple solutions but some things I over looked. I've mostly worked on 4 strokes. :crazy: ha ha. I'll try this out and report back.

[Billy Golightly]

Sounds like it could be an air leak to me. Do a search for leak down testing.

[1upfront]

I30 main is slightly big for that carb, in my bone stock 84250r I ran 93 octane, amsoil dominator 20:1 and a 115 main jet and it was crisp on top, not saying thats exactly what you need but I'm sure you need to go leaner on the main.

[Mikeproc]

i agree with that, a new plug for sure, you can check the reeds, but also 130 sounds too big, it does very depending on where you live, but i run a 120 here in ct

[freaksfix]

I30 main is slightly big for that carb, in my bone stock 84250r I ran 93 octane, amsoil dominator 20:1 and a 115 main jet and it was crisp on top, not saying thats exactly what you need but I'm sure you need to go leaner on the main.




wow.. 20:1... and you dont have any plug issues? ive run that oil but 50:1....

[Blown 331]

I just run the Honda synthetic 2 stroke oil at 32 to 1.
I pulled the reeds. I'm not real sure what I'm supposed to be looking for but I held the up to the light and looked at them from the carb side and I can see some light around the edges of each flap. I compared this the to the old reeds and cage out of my 85 R and could see much less light but still some. And yes the cages and reeds are the same for 84 and 85.
With the reeds out I grabbed the piston skirt and felt some movement so I pulled the head. It is the stock piston and is a bit loose. I shattered the piston on my 85, its fixed now but what a pain. I don't want to do that again so I puilled the jug. I'm gonna order some parts in a second.
There is no ring groove at all and with a digital dial caiper the top of the jug measures like 69.90 mm and the bottom I can get exactly 70.00. The piston measures like 68.5mm at the stop and 69.74 at the bottom. I was thinking of lightly honing myself and going with a standard bore wiseco. Does this sound ok? And I was also just going to buy Boysen reeds for an 85 R to use. I'd say piston, reeds and plug should do it. lol. And I'm not really throwing parts it, I see a problem with each of those items. Well not the plug but thats a given to change. Thoughts?

[iowarotax]

While you have it tore down, take the exhaust off and check for carbon buildup. I had a 84R that puzzled me for 2 weeks of checking everything. It idled and reved up great just sitting there. Once I got on it and took off it started to fall on its face about 3/4 into the powerband. It had a stock exhaust and silencer on it. The pipe and silencer weighed twice as much as they should of. They had wet carbon and gunk inside. Once I cleaned that stuff out, it ran perfect.

[Blown 331]

While you have it tore down, take the exhaust off and check for carbon buildup. I had a 84R that puzzled me for 2 weeks of checking everything. It idled and reved up great just sitting there. Once I got on it and took off it started to fall on its face about 3/4 into the powerband. It had a stock exhaust and silencer on it. The pipe and silencer weighed twice as much as they should of. They had wet carbon and gunk inside. Once I cleaned that stuff out, it ran perfect.


Good suggestion, I will check that out. I just scored a vintage hand made pipe but I don't have a silencer yet.

[toocheaptosmoke]

My R was also waaaay rich with stock jetting, I had to lean everything out a bit just to get it to quit fouling plugs. Since then I installed an '85 R carb and a CT pipe, has really helped out and feels like a different bike. Still using the stock silencer on the CT btw.

[factoryX]

buy a water cooler carb, new plug, and a oil change. that is what I would do.

[1upfront]

wow.. 20:1... and you dont have any plug issues? ive run that oil but 50:1....

The amount of oil has nothing to do with fouling plugs my plug is always the color of cardboard exactly how it should be and it runs so crisp it's unreal, it's all in your jetting, you can mix 50:1 and if your jetting is to fat you'll still foul plugs lol and in a 4stroke with rich jetting you can also foul a plug and thats with absolutely no oil in the mixture.

[Blown 331]

buy a water cooler carb, new plug, and a oil change. that is what I would do.

I've got a 1985 250R that I put a 36mm flat slide so I have my stock 34mm round slide and it's not even close to fitting. I see some people have done it but they either have to run different boots, open theirs up or really stretch the boots to get it on there. They would have to stretch so far it almost seems like they would tear.

I have the piston and pipe on the way. Now I just need to order gaskets and reeds.

[Dammit!]

Heat the boot up with a heat gun and it will most likely go right on.

[1upfront]

Actually the 85 fl350 intake boot is a direct bolt on and will easily accept a 34 mm carb they still sell them new on bike bandit. I have one on my 83trail r with a 36mm carb and one on my 84300r with a 39mm.

[Blown 331]

Actually the 85 fl350 intake boot is a direct bolt on and will easily accept a 34 mm carb they still sell them new on bike bandit. I have one on my 83trail r with a 36mm carb and one on my 84300r with a 39mm.

Looks like this is it.
13: INSULATOR, CARB
224801-001 Enter 0-99 $35.36

What did you do about the other boot, the one that goes to the air box? Stretch that one?

[1upfront]

I took a intake hose I had laying around from a honda del sol car and trimmed it down to fit heres a pic of mine with the 36 pwk.
http://i39.photobucket.com/albums/e183/lrdunlap/100_0220.jpg

[Blown 331]

I took a intake hose I had laying around from a honda del sol car and trimmed it down to fit heres a pic of mine with the 36 pwk.
http://i39.photobucket.com/albums/e183/lrdunlap/100_0220.jpg

Nice. I've got a 36mm flat slide on my 85 R.

And when I got home from work on Saturday the piston was already at my house. I still don't have the reeds or pipe but I put it back together anyway and with a new plug. Runs ok. I went with a standard bore Wiseco and honed it myself. The piston is nice and tight and the engine is much quieter.
I stuck the stock reeds back in, which I think are a problem but I'm hoping for the Boysens tonight. And once I get my pipe I think I'm going to just leave the stock one on for the time being and take the new one to get chromed! I know a local place that does it cheap. I think a chromed, hand made, sectional pipe would look great on an 84.

[beets442]

My buddy has an 84'R. I think 84' was the best(fastest)yearand 85' on the 350X's. Every machine runs a little different. Start at 32:1- SEMI-SYN break-in, full SYN after break -in!We tried full syn on break in and the rings didn't seat right...After a rebuild, we do a (plug chop.): Put a new plug in and run it at med-high rpms for about a 100 yards and look at the plug. Dark ,light, wet ,dry and when it's a coffee(w/cream) color it 's right. Lets you know how your mix and air is. Also keeps you from burning up a new top end. Plugs are cheaper..36mm seem a bit big, not saying it won't work but more problems to think about. It's already a kickass machine. If you want to sell it later, let me know. I would jet a little bigger than stock and go from there..Good luck. Be carefull shes a beast...Beets

[edog]

:pics: :pics: :pics: :pics: :pics:

[fidel]

put a new PLUG