engine reving itself !!!

[HONDA_ATC_FREAK]

I just rebuilt my 83 250r and I have been breaking it I rode it about 20min yesterday and it ran fine. Today I start it up and ride it maybe 15min and I'm slowing down so I don't splash through a mud puddle and I get in to first gear and then the engine starts reving itself up bery quickly 3sec max so I kill it so I don't blow the engine since I just rebuilt it. I then let it sit about 5min and started it up again and it did it all by itself again from the moment it started up. I then used a coin as a makeshift screwdriver to play with the idle screw and it didn't help. I don't have a clue whats wrong. anybody got any suggestions:confused:

[fabiodriven]

It's lean. You have an air leak or a fuel flow problem.

[HONDA_ATC_FREAK]

Well it's not lean It's really rich actually I put in a 140 main in it and have it 20/1 I actually need to jet it leaner. the plug is black and oily the exhaust is leaking at the header if that makes a difference.

[ovhonda1]

check the throttle cable routing. It may be pinched.

[HONDA_ATC_FREAK]

I'll do that but I thought of the throttle being stuck intantly so I worked the throttle and it moves freely. I don't know whats going on.

[zzmegad]

mabe it was running rich until it encountered this air leak, if your sure the trottle is in the right position, I think thats all it could be

[dcreel]

Were you running out of fuel?? Just a suggestion..

[HONDA_ATC_FREAK]

Umm I don't really know actually I don't think so, there was still fuel sloshing around when I had my little brother pull me home on my big red.I'll try looking for a air leak any suggestions on how to do this.

[HONDA_ATC_FREAK]

nope still had fuel in it it's not far from it though guess I got to go to the gas station and get robbed again @#$# gas prices

[Maico]

Doesn't matter what jetting or oil/fuel ratios you're running....if it has an air leak...it'll rev all by it's self. You said you rebuilt it. What did that entail?? Just the top end or splitting the cases??

[xr650jkallen]

mine did that yesterday and mine was the throttle cable adjusting screw was loose on the brake perch and actully vibrated tighter causing the slide to not bottom out

[leviblue]

air leak in the reed boot. you have a crack or a pin hole in the rubber boot. I'll bet my R on it

[Maico]

Crank seal on mag side, base gasket...even poor case sealing will suck air.

[Sick200x]

I had an old 250cc dirtbike that did that...I'd just had the cylinder bored and installed .080 over piston. (The old piston's skirt grenaded, and it sat for some years) Just flushed out bottom without splitting anything apart, but it cleaned out pretty nice. Cleaned and adj. carb. First day out it ran fine. Second time, it would run wide open at will. I'd kill it then restart it, sometimes wide open again, sometimes it'd act normal till you revved it, then wide open. Anyways...it turned out to be leaking crank seals.

[HONDA_ATC_FREAK]

I just rebuilt the topend and everything was torqued down to spec.

How do I find a hole in the boot if it is that? Do I just have to buy a new boot and see if it works.

[zzmegad]

take it all apart and inspect everything carefully, then assemble and make sure everything is sealed. or you can do one of those pressure tests, (kinda like a leak down test but opposite) and use soapy water to find the leak.

[zzmegad]

http://www.3wheelerworld.com/showthread.php?96856-Make-a-leak-down-tester-for-about-20

[HONDA_ATC_FREAK]

I just took the intake off and there was a crack on two of the bolt holes in the reed gasket I don't think this is the problem but I am making a new gasket right now so I know for sure it's not it if it isn't. I'll try and make this leak down tester.

[RubberSalt]

WOW only zzmegad was awesome enough and told him how to find the leak. OK, hears how more in depth. So you need to perform a leak down test. Basicaly, this pressurizes the crankcase/cylinder. Then you spray soapy water on it, if it bubbles, you have a leak.

Make leak down tester - cheap. Get a PVC cap that fits into your intake boot(where carb goes) and put a shradder valve in it(tire valve) (built mine for $3)
Take the exhaust off trike, seal off the exhaust. Take rubber or something and put it behind the exhaust flange.
Take carburetor off and put the leak down tester in the intake boot. Fill engine to 7 PSI of pressure, you can check at the shradder valve with a low pressure tire guage.
After pressurized, spray soapy water on; the leak down tester(make sure it don't leak!)
where the carb goes into the intake>reeds>cylinder
where the cylinder meets the case
All over the exhaust flange, make sure no leaks where it's sealed off
Head gasket
spark plug
Where the cases are bonded together, around the bottom of the engine
if it leaks - seals, flywheel seal first.

You shouldn't lose more than 1 psi an hour. You need to look closely around ALL the points listed above, sometimes tiny bubbles are hard to see. If you have power valves, you need to check them also, the cables and everything.

A leak down test is the ONLY way to know, for a fact, if you have air leaks. Carb cleaner does not show the tiny 1s. If you need to seal anything up, i HIGHLY recommend Honda bond. It is Superior to most everything, get it from a parts store for $6-8, dealers will want $15-20

[HONDA_ATC_FREAK]

thanks zzmegad for the instructions i'll build that.
ok I made the new gasket and it still does this so I guess it's off the the hardware store. Can I just put a piece of rubber behind the exhaust flange and torque it down I highly doubt my local hardware store is going to have that adustable freeze plug and the nearest big city is an hour a way so I really don't want to have to go just to get that.

[HONDA_ATC_FREAK]

Well I built the leak down tester but it is leaking like a SOB so I have to remake it.

[coolpool]

When I worked at a garage my boss used to use the oxygen from his oxy acetylene torch to find vaccuum leaks on car engines. He would slowly pas a slow stream of oxygen over the vaccuum hoses, carb base gaskets and intake gaskets. As soon as the oxygen hit the leak the engine would rev up. I've used WD40 with similar results, just a little more messy. Hope this helps. This will work only if you can safely run the engine of course.

[HONDA_ATC_FREAK]

ya buddy told me about that already but I can't run the engine it just rev's up to quick.

[RubberSalt]

It sucks, fix 1 leak and find another lol. I finaly got my 175 sealed up. It only lost 2.5psi in 2 days and 16 hours :)

I call it good lol - 1 psi loss a hour is good.

[bcredneck]

this may be a dumb question but do you have a airbox or a k&N

[bcredneck]

When I worked at a garage my boss used to use the oxygen from his oxy acetylene torch to find vaccuum leaks on car engines. He would slowly pas a slow stream of oxygen over the vaccuum hoses, carb base gaskets and intake gaskets. As soon as the oxygen hit the leak the engine would rev up. I've used WD40 with similar results, just a little more messy. Hope this helps. This will work only if you can safely run the engine of course.

that can turn a running motor into a grenade when i was younger and dumber i put my grandmas o2 tank on my freinds riding mower went way faster for about 2min then it blew a plug threw the plastic hood o2 needs nitrogen to be used in any motor with out destroying it

[HONDA_ATC_FREAK]

theres no airbox and a uni clamp-on filter not sure what difference it makes:confused:

[HONDA_ATC_FREAK]

Well I kinda got it to seal up the leak down tester doesn't leak, but the carb boot where it attaches to the leak down tester does. I guess I suck at making gaskets or my paper is the kind that is supposed to be wet to seal. My new gasket I made is leaking all the way around so I hope it was doing that on the old one too. I will get a new intake gasket instead of making my own now we'll see how that works. I didn't find any leakes on the engine other that the intake gasket. Hopefully thats my problem. Maybe the carb boot isn't sealing on the carb like it isn't sealin on the leak down tester too.

[RubberSalt]

When using the gaskets, put silicone on them to seal them up. Paper alone wont do it. The best is the permatex grey or the honda bond. I've used plenty of other kinds with good results. Just make sure it can withstand some heat. Once you fix that leak, test it again, you know.. the works.

The no air box with a clamp on make it run a hair leaner, less restrictive intake. pull smore air and less vaccum in the carb to pull gas.

[HONDA_ATC_FREAK]

Ok I was thinking of trying the honda bond on the gaskets I have a tube of it left over from putting the rear end together on my big red it's good stuff.

[HONDA_ATC_FREAK]

Well the hondabond on the gaskets didn't work and I can't find another leak so I am at a loss. Deepa man I really am starting to hate this thing.

[bcredneck]

theres no airbox and a uni clamp-on filter not sure what difference it makes:confused:

it leans out the motor cause it makes it easyer for your motor to suck air ive seen a few 2 strokes that need the stock air box to run right

[leviblue]

here's what I would do....1st I would get the manuel.....2nd I'd rip the carb down and buy a rebuild kit. .... 3rd I'd buy a new reed kit for it, not skimp and get stock reeds but buy the WHOLE V-Force kit. Boot is included too. ....4th if you are not running an air box WHY? Get one and a filter. you can make mods on the lid depending on your carb/jetting.....5th BUY GOOD GASKETS!!! not everyone is good at making them and there are differences for Honda gaskets. take your time spend the $$ and do it right the 1st time and you be glad you did. Remember your using 25 yearold parts and though they don't look it they can be warped and warnout. The right parts and an hour of your time and your bike will be running like new.

[RubberSalt]

Are you losing pressure anywhere at this point?
If yes, then you need to check the flywheel seal, that could be leaking bad. A leak there could destroy a crank bearing + anything else it wants.
If you lose less than 1 psi in 20-30 minutes id say it's good enough to run. You already found some leaks in the intake.

Honda bond wants a thin layer on the 2 surfaces being stuck together. thats from the jug -> gasket -> reeds - > carb boot, all needs hondabond between 'em. I went the extra mile and wiped a little around my intake, to make sure it had a good seal. After that, it quit leaking. Make sure your spark plug doesn't leak and your head gasket, as well as that exhaust isn't leaking. If you cant find that leak, you may want to double check the bottom side of the intake. If you don't see any leaks and dont hold pressure, check that seal.

[HONDA_ATC_FREAK]

How do I tell if the flywheel seal is leaking. I am not sure but I'm thinking it's leaking around where the carb meets the boot.
I'm only running no airbox because it didn't come with one when I bought it. I hate not running a airbox it sucks. I still can't get the @#%$#@ leak down tester to seal to the boot to know accuratly if I'm loosing pressure. The exhaust is leaking I said that earlier already around were the exhaust pipe goes over the flange. It was quite bad due to some bad brackets of the previous owner. I made some new ones and it fits better now.

[HONDA_ATC_FREAK]

Well the problem has been found my dad had the idle screw screwed as far as it would go. #$$% old men. So it was at as high an idle as it could be. I turned it 1 1/2 turns back and it runs perfect now. But while I had it running in the garage my dad saw that it was leaking gas out the overflow so my bowl is stuck open. If it ain't one thing it's another I tell ya.

[HONDA_ATC_FREAK]

Oh and to top it all off it's been perfect weather all week when I couldn't ride yesterday it was 65 today when i can ride it's 32 and rainy WTF.

[RubberSalt]

Do you live in kansas? sounds like kansas
leaky gas sucks - caught my trike on fire lol

Brother did another leak down test on his blaster - He saw oil running around the head, it leaked around the base gasket. He's glad he found it now and not later.. Told him not to use them cheap gaskets, so i made him 1 outta a paper bag lol

[HONDA_ATC_FREAK]

Nope I live in illinois, ya luckly it was cold so I didn't take off riding It could a caught on fire.

[TECATEMATT]

well least you know your bike is not possessed by goonies lol Damn 2 strokes are a pain, but the power is worth it!

[Backfire]

i get this because im running lean. you might have a vacuum leak, or you might have confused rich with lean. good luck either way

[atc007]

Ok! NOW that you THINK you are good to go.. Warm the bike up,let it idle,adjust your airscrew so it's idling at it's highest," happiest" point. Take starting fluid"ether",,NOTHING ELSE!. Spray your complete intake,cases,where you can get to them,and behind your flywheel. If there is a TINY pinhole,,it will suck that fluid in,and rev TO THE MOON! been at this 25 years,if she doesn't rev,,you do not have a air leak!! Jet her,clean oiled filter,,and you are good to go. Period! Good luck!

[HONDA_ATC_FREAK]

I'm assuming you take off the magneto cover to spray at the flywheel.

[RubberSalt]

Not tryin to sound like an ass, but the only way to know for a 100% fact is that leak down.

Spraying a flammable fluid around only finds the bigger leaks. It won't find pin hole sizes.

[x200x]

unless you already started screwin around with it, my r used to rev whenever it was runnin outta gas, but also if there was a plug in the line or carb it would do it with a full tank, maybe take off the gas line clean it and give it a good carb clean.

[HONDA_ATC_FREAK]

It's fine now just walked in the door from riding it the carb was the problem. thanks to everyone that helped

[fabiodriven]

Well the problem has been found my dad had the idle screw screwed as far as it would go. #$$% old men. So it was at as high an idle as it could be. I turned it 1 1/2 turns back and it runs perfect now. But while I had it running in the garage my dad saw that it was leaking gas out the overflow so my bowl is stuck open. If it ain't one thing it's another I tell ya.

Man I'm glad I didn't put much thought into this thread.

[HONDA_ATC_FREAK]

Ya tell me about it I was about to loose it and was even considering selling it.

[RubberSalt]

Yeah, that runnin out of gas makes it run lean, more power, higher rev.. more heat.