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Discussion Starter · #1 ·
I have an 88 big bear 350. I started a discussion a while back about a few problems i had. I managed to fix those..i think. Some pre history. This was a trade. A very bad trade i might add. I aas told she was a 2000 but later figured out its an 88.. ran fine on the day of trading which is why i traded. Next day wouldnt start and could see many many problems. Had to rewire and clean up electrical. Replaced all cv boots on front. New air filter. Spark plug. Cleaned the gas tank and filters put in premium gas and some seafoam. Cleaned the carb and replaced all parts and jets. After all this i was able to pull start it and get it going but she runs weird. I wasnt able to get the oil plug out for like a month as it was rounded. Finally got it off yesterday and did a complete oil change. The filter was completely covered alot of shit came out of the oil. Put new oil in went to ride it and its still riding weird.

Problems i still have on the bike. I am missing the air hose that sits on the gas tank and goes into the air filter box. I do have the crankcase breather hose just attched to frame as where it originally attaches to isnt there.. does that effect anything?

The muffler on it looks like its from a dirt bike. Its also lowered and pointed toward the ground so i cant go into water with it My wife has a big bear as well 98 and hers is stockand Its alot bigger...The slip on part of the muffler is smaller then my actual exhaust so they clamped it best they could i guess.. I covered some leaks in the exhaust as well. Im wondering what these effects have on the bike and operation...
How the bike is currently running... Im not sure if have the idle right or the air mixture screw but seems to be idling good? Lol but When in first gear she does have a little torque but doesnt seem to pick up much at all so i go into second and it feels choked up like im not going quick like i should so i go into 3rd and its not picking up much from there either. Best way to explain it is the power feels like its being held back somewhere and i try to push through it with more throttle but scared ill screw it right or blow something lol I also notice the motor and exhaust gets extremely hot within 15 minutes of starting and riding.
Im about to give up on it lol i have to much pride to take it into a shop and pay to get it fixed when i know im more then capable to fix it on my own. Just dont know if the muffler is my main problem or what is causing the lack of go in the bike.

Thanks to any help i get!
Amber.
 

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The muffler is causing your problems most likely. Especially if you are running a stock carburetor with stock jets.
That muffler flows different than a stock muffler. The intake air and fuel will need to be "tuned" to that flow by rejetting the carburetor. And depending on the flow of that muffler, it may never be able to tune it via jetting.
 

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I would check the timing and the valve lash....just say'in it may be a compression deal with valves not closing fully.
 

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Discussion Starter · #4 ·
Ya i did a compression test today its at 90 psi which is obvi low. I didnt have time to try putting oil in the spark plug hole though to tell me if its rings or valves or not yet. It wouldnt surprise me if valves are out of spec... Im ordering a new intake manifold as well as i dont trust the one that is there to not have any slices or holes... will definitely let you know what i come up with in the next couple of days.
Also how do i check the timing. Can i possibly get a step by step quick walk through from someone please and thanks!!

Also Dezz i friggin hate that muffler.. its completely useless. Been trying to find a used muffler but anywhere i look the first thing everyone jumps on is the muffler where i live lol im really not wanting to pay 200 for a mbrp muffler and also having to replace my exhaust. Used is in my price budget so until i find one i cant change it!! Its killing me lol
 

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Ya i did a compression test today its at 90 psi which is obvi low. I didnt have time to try putting oil in the spark plug hole though to tell me if its rings or valves or not yet. It wouldnt surprise me if valves are out of spec... Im ordering a new intake manifold as well as i dont trust the one that is there to not have any slices or holes... will definitely let you know what i come up with in the next couple of days.
Also how do i check the timing. Can i possibly get a step by step quick walk through from someone please and thanks!!

Also Dezz i friggin hate that muffler.. its completely useless. Been trying to find a used muffler but anywhere i look the first thing everyone jumps on is the muffler where i live lol im really not wanting to pay 200 for a mbrp muffler and also having to replace my exhaust. Used is in my price budget so until i find one i cant change it!! Its killing me lol
Look for step by step f.s.m. here.
 

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Discussion Starter · #8 ·
Can someone please tell me that shiney metal in between the cylinder head fins is not a blown head gasket??!!?? What is that! Lol thanks for any help. The bolt you see below is the chain tensior. The metal showing is just under my intake flange connected to the motor and carb. I have other pictures if needed. I also adjusted my intake valve it was super tight. I am still getting 60 psi which is low! Am i looking at a big motor problem? Its an 88 not sure if she is worth putting alot into
 

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That's just an ear of the cylinder head gasket. It's there to hold to help with installation.
 
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Discussion Starter · #11 ·
Thank god!!! Okay maybe you can help me with this as i seriously cannot figure it out! And youve been most responsive and best advice i might add!. So i did the compression test. My blonde kicked in and i forgot to do it with throttle all the way open. I got a 90 psi reading there. I did it with throttle open. I got 60 psi. Even worse... I put some oil in and it stayed at 60 so because it didnt go up after putting oil in thats telling me its valves so i checked both intake and exhaust. The intake was super tight so i had to re adjust. I also had a hard time getting to tdc. Anywho valves are adjusted i rechecked so should be good there. I replaced the intake manifold flange as there was a gap as well as a big tear. Still getting a 60psi reading. Why is my compression so low still?? Im also having issue getting the bike to start from pull start. I feel compression. It rolls over just doesnt fire. I got a new spark plug just ad still had to kept lifting the decompression lever and having to pull over and over with no luck. So i put the old spark plug in that was full of soot tried it 3 times the 4th time she almost fired up. I cant figure out why it wont start now. Ive cleaned the carb multiple times. Did the oil change..it was unbelievably bad so was the oil filter. Could it be something as little as my battery not giving it full load? It is brand new... Any help is totally appreciated. Running out of ideas and tests to do to narrow this down. Im going to put another picturw up of my time chain. I have crankshaft at tdc but want to make sure it looks like its on time? Looks a tiny bit past to me
 

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Discussion Starter · #13 ·
Oh and the spark plug wire/connector for the top of the plug i noticed is a little loose will that cause it to loose spark and may be part of my starting problems?
 

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Without actually being there in person to help troubleshoot, it's a guessing game.
What trouble did you have getting to TDC? All you do is remove the timing plug on the lower engine case and line up the flywheel timing mark through the hole. To make it easier, I always remove the pull cord and use a socket with breaker bar to line up the timing mark. That gives me more control. Then I look at the camshaft timing mark. If the cam timing of way off, then I know I am 180° off timing. Rotate crank another revolution and things should now all line up. Adjust valve clearances at this point.

That camshaft timing mark is a little off. That is caused by a stretched timing chain.

There is several things that could cause low compression. Even though your valve clearances are now set correctly, this does not mean the valve seats are sealing correctly in the head. They way require lapping. Although leaking valve seats ate not usually picked up on a regular compression test. That is usually found on a leak down test.
Your piston rings could still be worn, even with engine oil down the cylinder.

Did the engine run before you did all of this work? It was my understanding that it did. If the engine did run before, then something else happened or you did something wrong. Are you sure you were not 180° off timing on the crank before you adjusted the valve clearances? Did you just use the camshaft timing mark to check timing alignment? If so, redo the complete valve clearances check or adjustment again. I've seen people do this before. It happens.

The spark plug wire being lose can cause running issues. That should be fixed.

How good of a spark are you getting? Is it bluish/white spark or yellow? You want a white/bluish spark.
 

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Discussion Starter · #15 ·
Okay you clearly know your shit! Thank god lol yes it was running before. When i traded it she was running great that night, after i killed it it would start with electric no problem. Seemed to be running good considering the crappy little exhaust can. This was in feb. Dead winter here in ontario. She wouldnt start up with electric start she wouldnt start at all actually. So i looked at wiring it was a damn mess they took the main fuse out and hard wired together both wires so there were no fuses at all on it. I put a 30 amp in. Did what i could to clean up the wire mess. Everything is connected where its supposed too. Starter and solinoid kept clicking anytime i pushed the start button so i took the pull cord off my wifes big bear as her 98 is in amazing shape runs with electric so i took what i needed haha. It started with the pull start after a few tries and playing with the choke. I notice when the choke is fully out it stops my pull half way through dead stop. So i hardly use the choke now because if that reason. When i was riding i noticed it was lacking power over half throttle in first to 3rd gear as i didnt try 4th and 5th it was running shitty enough. So i replaced all the carb jets and what not with a new kit and bought new intake for in between carb and motor. Replaced front cv boots.checked to make sure back braake wasnt stuck. Then started with the valve adjust ments last week you are right i may have messed it up. I had to turn the crank the oposite way for it to even stop on tdc 5hen i did it the proper way to crank and it found tdc finally... Adjusted the valves. Chrged the new battery put a new plug in and sound like no fire as ina good enough spark. Spark plug had gas on it. Had the idea to put the old sooty one in did a few arm killing pulls and about 3rd pull she almost fired up and had smoke come out of ky holes where the exhaust connects lol im lost. So i should try tdc again and adjust my valves clearly as i feel i fucked up lol. To bad you dont live in muskoka could really use someone with your expertise with this girl!
 

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Discussion Starter · #16 ·
Re did the adjustments for the valves. Inatke need a bit of an adjustment and exhaust valve was in spec. Timing chain looks almost a quarter past where its supposed to be. So its off a little. How much will that affect the bike performance and starting? I noticed today after hitting the start button once or twice then pull starting i almost had it started. Im picking up a new ignition coil tomorrow as its loose on top the spark plug. So hopefully that helps get it started. My circuit breaker has a plastic red spot in the if it and that is broken, should i replace the breaker too could that be part of my starting problem? I cant narrow it down. What do you honestly think the bikes issues are and where i should go next from here? Sounds **** it wants to start but looses power or spark and wont stay fired. Tested battery under load and i think it was good. When i tried the push button it droped to 11 volts though. Dont know what that implies. Thanks for any help..again...lol
 

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If its trying to start, address the timing problem next. The valves cannot be closed fully if out of time, or adjustment. How did you adjust the valves with a bad chain.
With a good chain I use a straw down the plug hole trick to determine t.d.c., then I checks the marks to know the top end is properly timed to the crank. Then I set the valve lash to the wide side of the range to make damn sure the valves are fully closed when the plug fires. If the timing is off as much as I think the valves can be starting to open when the plug fires, thus you get a hard start due to low compression.
 

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Discussion Starter · #18 ·
Im so confused now lol okay so i turned the crank over twice til it hit tdc and the t and lines are lined up on the crank. The picture above of my chain is what it looks like when at tdc. I adjusted the valves at tdc as the manual said. So im confused on what you are saying i should try next? What does the straw do and where do you put it and what do you get from doing that?
 

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Discussion Starter · #19 ·
Would you say that pciture showing it a little past the line on the chain is out of time? Even being out that little will it mess with the starting? It homestly sounds like not enough spark when i pull it. She almost started yesterday i know my full air ratio needs to be adjusted but 2 turns out wont work i have to turn it out more for it to get close to firing. So i do knot the air fuel ratio is a problem but i cant set it properly until warm so im troubleshooting where i can with half turns
 

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Discussion Starter · #20 ·
Im quite the handy woman but this is driving me nuts. Especially since it was running 2 months back before i started cleaning it up and replacing things properly. Should of kept it jimmy rigged aparently lol
 
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