1999 fourtrax 300 running rugh

3032 Views 20 Replies 4 Participants Last post by shadetree, Aug 22, 2017

Tractorboy

Discussion Starter · Aug 19, 2017

hello I recently perches'ed a 1999 honda fourtrax 300 4X4 and it was burning oil so I got a gasket kit and took the engine apart removed the old gaskets and seals and installed the new ones then put it back together and adjusted the timing then I went to start it and I had to give it a bit of throttle for it to start and the it would run really rough. Why? It allways ran vary well and smooth.

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SamUK

· #2 · Aug 19, 2017

So you've replaced valve stem seals and head gasket?

Is the timing correct?
Are the valve clearances correct?
Have you cleaned the carb as a matter of course after taking your motor apart?

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SamUK

· #7 · Aug 20, 2017

Here's the route I'd go next...

Set valve clearances, perform compression test (with throttle wide open), then thoroughly clean the carb. IIRC the compression should be somewhere between 170 & 201psi.

Even if you comp test comes back a little lower, let's say 160 for arguments sake, it should still run relatively smooth.

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SamUK

· #9 · Aug 20, 2017

Tractorboy said:
What are the valve clearances

Off the top of my head I can't remember, you'll find them here though
http://www.hondaatvforums.net/forum...nual-help/50817-service-manual-downloads.html

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SamUK

· #13 · Aug 22, 2017

Tractorboy said:
Well I was right the timing was off so I got it right and it still ran a little rough so I cleaned the carb and now it runs great. Compression cold is 180 psi and hot is 170 psi thanks for your help

Good work Tractorboy, compression is steering towards the low side but if your not a hard rider it should see you another season before you want a top end build.

Since you've had it apart doing gaskets etc now would probably be a good time to do an oil and filter change too, maybe throw a new spark plug in at the same time ;-)

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SamUK

· #16 · Aug 22, 2017

170 is his warm reading, 180 cold so Yeah.. it's on the lower side of the FSM spec. 176 to 201 i think it is.. it may run at 100 but it's not right, there underpowered as it is, I dread to imagine what 100psi compression is like!

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SamUK

· #18 · Aug 22, 2017

I agree, it will run, but it's not right, hence Honda specifying 178 to 206. I advised the OP as per the FSM specs ;-)

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SamUK

· #20 · Aug 22, 2017

Here here.. We'll agree to disagree then lol

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