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Discussion Starter #1
Good Morning. New to group, new to ATVs(in my 45 yrs, my but has been in a seat for maybe 25 minutes before).

I'm mainly a car guy(have rebuilt several Small blocks, transmissions, differentials, etc) but have wanted a quad since I was in HS. I live in southern Indiana and will use it mainly around my 3 acres(hope to have access to 40) for fun and utility use.

Bear with me, I am long-winded...

I bought a basket case 98 450S Foreman from a friend last night who was at his last legs trying to figure out what the dealer diagnosed as a timing chain slip. He was afraid the engine needs the bottom end rebuilt and he had spent too much money on it already...so I made him an offer and he took it.

Symptoms are it will start and run, but won't respond to throttle, won't idle very long(seconds) until it dies. I tried starting it several times when I got home with it and noticed a blue flame emanating through the carb as it dies. You can hear the starter(I think) do a 'sproing' sound as it dies too. It's very hard to pull start too. I'm a big guy...and it is tough.

So the dealer diagnosed a timing chain failure. My friend refused to pay their '1500 to start' quote and did it himself. He's a tinkerer and has rebuilt car engines in the past successfully. Very meticulous. So he tore into it. Put new timing chain, tensioner, inspected piston, bushings, etc. He replaced everything he could as he had it apart. He does/did product validation at an engine company...so is familiar with inspecting torn down engine parts. He also put a new CDI box, new main harness(found a short in the old one), new carb. He was planning on keeping it so they are all Honda parts. The timing chain was another 'odd' brand but said it was a subsidiary of Borg-Warner or something. Said it wasn't a cheap china chain

He was afraid the bearings were binding in the bottom end and the engine needed a bottom end rebuilt. At that point, he was done. He had replaced everything he thought could impact the timing and it still acts the same as before the work.

I think that it if was bearings in the bottom end, it would respond to throttle, it would at least act like it wanted to run...and would get worse as it heats up.

So reading the Clymer manual, there is a little blurb(keep in mind, I know little about motorcycles or ATVs)...it said 'if it is backfiring, your timing is off and is non-adjustable, check <several things> as well as the key on the flyhweel to ensure it is intact'. <--something to that effect. My friend never pulled the engine, he did all work in chassis and I trust he did it right(unless there is some trickiness to it, but my presumption is he did it to the best of his ability right)...so I am thinking he may have a sheered flywheel key and not caught it. I don't know where the flywheel is, but my assumption is it's on the backside of the engine. He said he had the recoil starter off and looked at it at some point...not sure the timeframe of that. Looking at Clymer, recoil start, then stator<?> then you have another cover to remove before you see the flyhweel. I don't think he got in that far.

As I'm new, though, I am open to any other ideas before I pull an engine out and tear into it...but my general question is...

1) I assume I need to pull the engine to pull the flywheel
2) I want to get a gasket set on order. Thinking full engine set as I have no idea what I'm going to get my hands in to....any manufacturers/warnings of places to avoid? Best placest o get parts, etc.

Thanks!
Greg
 

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To get the rear cover off the motor, to get to the flywheel, you either have to pull the motor out of the frame or take the rear swing arm off. The path you are headed down sounds like you are pulling the motor. You can get the front cover off with the motor in the frame if you want to double check the cam timing.

Search the internet for honda foreman 450 service manual pdf to find and download a manual.

You can get all the oem parts and gaskets you need online from any number of parts places.
Two I use a lot are rockymountian atv and partzilla
Both have parts diagrams that are very helpful
 

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Discussion Starter #4
Thanks guys! I appreciate the help. It was tricky as I searched out a forum to find one that was 'alive'...as I found a couple that were 'last post 10 mo ago'!

Yes, I am 3 bolts and the exhaust(and a strong back) from getting the engine out. Wish I could go to Walmart to buy gaskets as I'd grab them and my brothers and I would rip in to it this weekend(heading up there after 6 months due to 'Rona'...). I'll get some on order today as I expect to have it sitting on the bench by supper time(back willing)

I figure I trust the guy I bought it from did it to the best of his ability in chassis. He was standing on his head. It would be easy to get off a tooth putting chain back on. I also don't know when he had flywheel off. Whether it was during this change out or before. He said he did all this work in the chassis. Possible he rebuilt the rear swing arm(he did that I know) this past winter too and pulled flywheel at that point. He is going to give me the puller MOnday when I see him. He forgot when I picked it up. I just want to recheck everything while I"m confortable and honeslty, it took me about 2 hrs to get to this point last night as he had a lot of covers off already.

Thanks again and have a great weekend!
 

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Discussion Starter #5
One question I had, though. Is there a pickup on the flyhweel for the timing/spark indicator? How is the keyed flywheel important to engine spark? I saw lots of pics, but no 'this is the fundamentl function of your quads timing/cdi/ignitions system. Haven't seen it in the Clymer's manual. I have hte pdf of the Honda FSM downloaded. I'll search that, maybe more info is in there.
 

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Spark timing isn't adjustable. Yes the flywheel is keyed to the crankshaft. If the key or keyway is buggered up that is an issue. Cam timing is something that can be off a tooth. If it doesn't have a new cam chain I would replace it.
 

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Thanks guys! I appreciate the help. It was tricky as I searched out a forum to find one that was 'alive'...as I found a couple that were 'last post 10 mo ago'!

Yes, I am 3 bolts and the exhaust(and a strong back) from getting the engine out. Wish I could go to Walmart to buy gaskets as I'd grab them and my brothers and I would rip in to it this weekend(heading up there after 6 months due to 'Rona'...). I'll get some on order today as I expect to have it sitting on the bench by supper time(back willing)

I figure I trust the guy I bought it from did it to the best of his ability in chassis. He was standing on his head. It would be easy to get off a tooth putting chain back on. I also don't know when he had flywheel off. Whether it was during this change out or before. He said he did all this work in the chassis. Possible he rebuilt the rear swing arm(he did that I know) this past winter too and pulled flywheel at that point. He is going to give me the puller MOnday when I see him. He forgot when I picked it up. I just want to recheck everything while I"m confortable and honeslty, it took me about 2 hrs to get to this point last night as he had a lot of covers off already.

Thanks again and have a great weekend!
well..you found us !, www.atvhonda.com
 
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