1998 CR80 - Running lean but smokes ALOT

[shintoryuu]

Please someone tell me if this is the wrong forum . Anyway, I just got back into riding after a long time away, and don't remember much in terms of repair. I just purchased a 1998 CR80 for my girlfriend, and had to change the clutch since the last owner (35 year old wife) decimated it. Afterwards, I put a pro-circuit pipe and silencer on, and jetted it a bit richer. The problem is, since then, the bike has always seemed to run a bit lean, in that it revs quick and has very little power. However, it has AN INCREDIBLY excessive amount of oil coming out of the silencer (and oozing out, as well), and looks to be rich. As I and her do most riding in the desert, as the day goes on, the problem gets worse as it gets hotter, to the point the bike can barely inch foreward. I'm guessing it may need a top end, but don't know. Please, someone help.. I live in SoCAL, and shops down here charge more than the bike's worth just to diagnose =p. PS - around the pipe, it seems to have a very poor seal, and oil is all over the cylinder (even more than most 80's)... could it be because of a bad leak at the flange? Thanks!

 

[Glitch]

IMO - Its sounds too rich. As the day gets hotter, it becomes richer because the air is hotter and there are less molecules per cubic unit than it is when its cooler out. So therefore there is less air to fuel, making it rich. So start to lean the pilot/slow jet, needle, and main jet. Do a search for jetting, there's alot of good advise in other threads. You know your running lean when the bike goes bwoooooooaaaahhhhhhh. And too rich when it crackles and lurches and dont want to go.
I think that you posted it in the right forum

Jim

 

[shintoryuu]

Hmmm.. that would make sense, especially with the increase of the problem as the temperature rose. My only worry was, it seemed to show the lean symptoms (quick revving, the bwoooooaahhhh sound, with smootheness but lack of power, in comparison to the bogging of being rich). Or at least, that's what I remembered them to be. Or can those also be symptoms of being rich? (flat, uncharacteristical power, very smoothe with no personality, just goes with no powerband, and lacks any tire spinning uuumphh). Thanks

 

[dell30rb]

You have a very big problem. My cr80 has an incredible powerband, with a very hard top end hit.it spooges and smokes a little, but otherwise runs very strong. If the pipe and silencer are the only mod's done to it, change the jetting back to stock, and see what happens.

If that dosent help, you could very well need a top end. If you can change jets on a carb, you can easily do a top end.

My manual recommends jetting specs for different altitudes. Give me yours, and i will tell you the manual-suggested jetting.

 

[Durt Cycler]

What type of 2-stroke oil are you running and at what ratio? I ask this because SOME oils will smoke alot more then others (i've experienced this). It sounds like the bike is EXTREMELY too rich that's why you hear the "bwooooaah" sound. Extremely rich jetting can sound like a lean sympton. I would do what dell says and go back to stock. Also what heat range plug you using? If your running a 10 switch to a 9.

 

[dell30rb]

I second the switch. I use a 9.

 

[shintoryuu]

Changed the jetting back to stock: Felt VERY VERY lean. I'm about 215, and it could barely carry me. Still smokes a ton though, almost as much as it did with the richer jetting. As for the oil, I'm running Maxima at 32:1. For the plug, BR10EG. Tried moving it down to a 9, but the engine seemed to get worse and somewhat hotter. It's breaking 90 when we ride (up past 100 sometimes), which may be the problem. I'm beginning to wonder if it needs a top end.. I hope nothing worse. Never heard or seen a bike act like this before. I'm also going to go switch out the pipe for the stock.. the stock has a damn hard hit that would pull the wheel off the ground instantly... just made it really hard on my girlfriend who is learning on it since using that narrow of powerband in the sand is hard as heck. I'm still also wondering if the seal around the flange has anything to do with it... there is ALOT of oil escaping down there, and the cylinder is getting covered in it. Out here, the bike is running top gear full throttle alot, so I don't know...... PS - This is a PC pipe and shorty silencer I was using for extra low end. Oh, and one last thing that may contribute. When I bought it from the original owner, I was asking, and she told me that for the 20 or so times they ran it, they ran it with 87 and 89 gas, no 92 (probably cheaper gas at that since it was near Mexico). Could that have damaged the cylinder? Thanks everyone!!

 

[kdxtaz]

You should do a compression test, very easy to do. If that checks out ok make sure the powervalve is working (oh wait - does that bike have one? :think: ). A leaky exhaust flange would rob a little low end, but not much else. You should also do plug chops at various throttle positions to check if it's rich or lean. Sometimes the aftermarket pipes will throw the jetting way off. If you think it's lean, try runnin' it once with the choke on. If it gets better, it's lean . Worse, it's rich. Hope all this helps & doesn't mess you up more :eek: !

 

[shintoryuu]

Sounds good.. I'll go purchase a compression tester tomorrow. Does anyone happen to know offhand what the optimal compression is for a CR80 (1996-2001 Range)? My service manual is about 300 miles away. And, approx at what percentage of that optimal compression is it low enough to need a rebuild? Thanks very much!

 

[David Trustrum]

I almost don’t want to get involved as my head is hurting but I will drop in say a couple of words & unsubscribe.

Fix the flange leak it can’t be helping

First off the condition of the rings won’t cause it to smoke the way a 4 stroke does as the rings aren’t controlling the oil. It probably does need rings by now so pop the top & measure/inspect it. Leave it too long & damage will occur. A compression test is a bit pointless for that reason & should only be used as a diagnostic of the extremes or trends.

Secondly remember that jetting is throttle position dependent. It is easy for the bike to be rich on the pilot lean on the needle & rich again on the main or any other combination so you might be getting spooge from richness but be lean elsewhere.
Check the airbox for leaks first anyway.
Re pack the muffler, perhaps it is so full it will smoke no matter what.

An 80 in the desert? The poor thing :scream: , no wonder it’s overheating!. Stop being a tightwad & buy her a reasonable size bike. :moon:

 

[whyz]

The manual I have says engine Comp. is 100-125 psi.
Honda makes a new flange for these bikes,they cost 50 somethin.
Suppose to be better than what is on there.
I tried looking for it but can't find it at the moment.

I dont even let my son ride that YZ125 in the sand.
And he's 14 now at 120 lbs.
Next year we will both be getting bigger bikes just for that purpose.
See Ya..

 

[shintoryuu]

David - Thanks for the jetting information. I have the bike restored to stock now and I'm fiddling with the jetting to see if that is the case. Also, airbox has no leaks, and the muffler only has 5 or 6 hours on it. As for being a "tightwad," I would have gladly spent the money on a 250F for her, and still offer. For some reason though, the idea of a full sized 125 in loose sand for a 130 pound beginning woman rider just doesn't appeal to her :silly: .

Whyz - Thanks for the PSI information. I'm going to check it, but I'm going to tear it down anyway and see what's there, just to be on the safe side.

Thanks everyone for the help; I'm going to spend the next four or five days trying everything, and repost if none of that helps (which I doubt).

 

[2smoke]

Shintoryuu when i wuz a young fella and rode $150 specials I bought a YZ80B for......$150. Top end was really worn bad....smoked....revvved hard and would go reasonably for 30min then barely run as it got hotter and hotter (we mainly ride in winter no snow here....actually you can nearly all year round if you want to) and it would barely carry me. Me thinketh the top end is very slappy. Dont fret its not a four banger. Cheap as chips and pretty easy to do.

 

[badnws2]

if you are sure that the bike is running lean and you have checked to make sure that the pre-mix is at the right ratio and checked the compression , you might want to check the crank seals this would cause the problem you are discribeing the one on the clutch side . good luck.