Hello All !!

It's like the third time I ask the question, because I did not have time before to investigate, but
I'm ready to fix up my problem .. Well, before splitting the engine, I just want to be sure the problem
is not something stupid and easyli repairable!!

Okay, my quad is a Foreman 1998, used one, with about 3000 km on it ..

I've found that my engine does a kind of noise, it's more specifically a sound of vibration, I thought at first that
some plastic was vibrating on the engine, so I tried to hold the plastic around the engine and I found that the
cause of the problem is coming from Inside the engine . ..

The location of the sound, is near the Recoil Starter, like if it's coming from under or on top of the Hex Bolt (the hole) that
we use to see if we are in TDC on the piston when Adjusting valves ...
I don't know what is in this region, but I know the sound follows engine RPM ....

It is the only place I heard a strange noise on the engine . . .

Could this be a Normal wear of the engine !? . .

I did an oil flush today, and found some very microscopic metal particles in the oil, I wonder if that is normal wear .. .

A part from the noise, the engine seems to be working properly, except from those nasty Backfires . . .
I've adjusted the carb .. The backfires seems to be less frequent, but I have those random backfires when
I shutdown the engine, I have a blue flam about 10 inches in size that does a FFffffpop when I shut the engine . ..
Could this be a leaking Exhaust valve!? . . .
I am not an expert in engine internal parts . . . So I'm just trying to learn !!

Thank you for your patience, I know I ask this question for the third time . ...
[img]i/expressions/face-icon-small-tongue.gif[/img]

 

Oh sorry, I forgot to say . . . .

At Idle, I don't hear the noise ... .

The noise starts when I push the throttle . .. then it follows engine RPM and becomes more loud as RPM increase .. .
At certain RPM, it's louder, but that could be resonance . . .
The noise is present even at neutral or in gear . . .
So I don't think it's the transmission, or it is the clutch .. . ? ..
I've checked my Oil filter, and I have some kind of fibers trapped in it, not much . . . That is Clutch compound, am I right ?! ..
Normal wear ?! .. .

About the engine condition, I don't have abnormal smoke coming out or anything like that, except for the backfires like i said..
I don't think I have major head troubles . .. The engine is powerfull .. I should do a compression check when I find someone with
the tool . ..

 

Ah, there are quite a few things this could be from what you are describing. Could be bad bearings, worn piston, timing and so on. Id suggest getting a manual and looking into it.

 

Hahaha quite funny since your nickname is Manual .. 8] ..

Well, my guess is a bad bearing .. It's just very hard to tell!! Anyways, I think I'll dismantle the engine, but
that scares me a bit, since that will be the first time ever I do that!!!!

Is there anything I should know about it!? ... And, Yeah I have the manual ...

Do I have to change anything that I'm sure will break when splitting the case, like the gaskets or something!? ..

What parts should I look at!? ..
Do the parts are cheap, for example, a bearing!? .. Or if it's a gear or the clutch . . .
What are the principal things I should look at!?

Thanks !!!!

 

Take care ot the backfire problem....adjust the mixture screw out 1/2 turn, look for intake leaks, and exhaust leaks. Do you have the air box lid on?
What kind of oil you running? What viscosity? Do you have the correct oil filter, and installed correctly?
Is the recoil jamed up with mud? does it work?

 

For the carb, I've adjusted the mixture 1/2 out already, I must say, I've adjusted it like 5 times, from scratch, by what the
manual suggest.. No success. . So I just enrichen the mixture every time by about 1/2 turn .. I'll turn 1/2 turn out again to see ...

I have this quad since about a year from now, and I don't know how the guy was driving it ..
For sure, I have backfires since I have it .. My exhaust was broken last summer, so I've opened it and remove a
loose piece in it (- A tube with a plate at the end, now the muffler is just empty with a kind of star shape at the end, That is the spark arrestor, I think ? -) ... Reweld the thing back . . . I did not looked for gaskets or anything where the pipe is connected to
the muffler, but I don't think that the problem of backfire is there... BUT, that makes me remember that the vibration started from there!
But it seems to be engine related, maybe I'm just wrong . . . I'll remove the muffler to see if the vibration is still present..

Maybe I need to rejet, 'cause the muffler has less restriction .. What is your opinion !? .. And I think the carb is set to stock default
position on the needle ...

I've removed the carb to clean it, but it did not removed the backfires . .. For that, I think the intake is not leaking . .
I've checked the exhaust to, and I don't think it is leaking at the head too ..

Is it possible that the valves are leaking, and that it could be the source of all the problems !???


The Air Box Lid is on ..
The filter is clean and oiled.
Normally I put Honda Brand oil ..
But I started putting 15W50 Mobil-1 synthetic like, yesterday, and it still make backfires..
Less frequently, but still there, when I depress the throttle from about 1/4 to Zero . . . (Pilot ?)
The Oil Filter is installed correctly.
The Recoil Starter is functional, but the recoil spring seem to be weak .. I'll remove the cap and seek for problems there...

 

AAAAAAAAAWHHHHHHHHHHHHHHHHHHHAHA!!

I FINALLY FOUND THE @$%^#$^##$ PROBLEM . .

Stupid Skid Plate that was loose.. .Damn, I feel Dumb . ..
After puting my hand everywhere, and burning myself everywhere, I've found it !
8]]]

No more vibration and noise . .. Just valve ticking, but seems normal . . .


Thank you all for your help . . ..
8]

 

Glad you found the noise, now the back fire problem. It could be due to the exhaust having low restriction, could also be an adjustment or bigger pilot jet.
When you adjust the mixture screw, the 1 1/2 turns out is just a starting point. After the motor has warmed up, slowly adjust it in until the rpms drop. From there, start counting the turns, out, until it drops rpms again. Halfway in between is a good spot for it. If you get to 3 or more turns out, then you need to go one up on the pilot jet.
Honda recommends 10w 40, and it should be an oil rated for wet clutches.