there are two problems with it the main problem is that at high rpms it seems to pop in and out of gear, is this a simple clutch adjustment or it it more serious with warn parts.

The second problem is a rattling when the engine is revved, is it possible that it is the cam chain or is there something else to check

 

Welcome to the forums Billy177.
As for the popping in and out of gear, have you noticed the clutch slipping at all say, after shifting into any gear? I would say the clutch maybe slipping. Clutches do wear out. They occasionally need to be replaced. It's not a serious problem. Not a big deal to replace one if you have a manual to follow.

As for the the rattling that sounds like it may be a serious problem.

 

well the rattling turned out just to be a loose bolt on the frame however as far as the popping out of gear is concerned it seems that it may not be the clutch after all as it is much worse when going down hill then any other time. at low rpms its fine just when the rpms are high is when it pops in and out

 

<div class="FTQUOTE"><begin quote>Originally posted by: Billy177

well the rattling turned out just to be a loose bolt on the frame however as far as the popping out of gear is concerned it seems that it may not be the clutch after all as it is much worse when going down hill then any other time. at low rpms its fine just when the rpms are high is when it pops in and out</end quote></div>

POPPING ..IN & OUT of gear?
I have experienced a machine popping out of gear but not back in gear.
What gear are you in when this happens and how high of an RPM are you relating this to?
Is the machine screaming like it was ready to blow?
Or is it the Hi RPM just before shifting in the normal power range?

If it was just popping out of gear and doing it in just a particular gear like 1st or 2nd gear, I would suspect one of two things that the shifter is not getting the gears fully engaged after shifting, due to the shifting plate retaining bolt loosened up which is on the face of the shifting drum or the dogs are warn on the face of those gears.

Now you mentioned IN & OUT of Gear which leads me to the clutch, which will feel like it is not pulling or holding back as you are accelerating up hill or decelerating down hill respectivly speaking.

Detail your description please so someone can refine a solution.
...

 

It happens in every gear when the engine gets into the powerband It feels like a chain is jumping and catching again sort of thing, however I adjusted the chain so it is tight.

 

Chain Jumping huh I forgot about that possibility. When you adjusted the chain did you make it banjo tight or did you give it some slack say 3/8 to a 1/2 inch play. I wouldn't recomend Banjo tight.
If it were that, then it would have jumped when a load was applied and not just related to HI R's.
Try to simulate this by a hill climb and see if the strain produces the same feel as you have been describing, also try it in a higher gear.
I am imagining, from your description it is a chug or a jerking type feel, something like riding the rails of a train track?
Real Long shot:
Did you check the front and rear sprockets to see if they are badly warn?
The sprocket teeth would look like they are taking the shape of the teeth of a circular saw blade.
Maybe a stretched chain, with the machine off, block up the rear, put the machine in neutral slowly by hand rotate the rear wheels see if you feel any stiffness or a slight binding when revolving the wheels. Watch the links of the chain as they pass over the sprockets see if they line up smoothly with the teeth, and not flop back into place as the links pass over the teeth.
Like I said it is a long shot.

 

I checked the chain today and it is tight so I dont really know what it could be

 

Did you check the front and rear sprockets to see if they are badly warn?
Spin the rear wheels to see if there is any binding?

 

yes both sprockets are good and there is no binding

 

OK Bill like I said it was a longshot.
This all leads me back to the clutch..

Since it is a semi automatic and it is a wet clutch.
Check the oil level and also verify the oil is clean.

Do you maintain regular oil changes? Since you have not mentioned anything about service maintenance, I am assuming you have not taken very many steps in this direction.

If the clutch is deprived of a ready flow of oil, at hi R's it may be starving
Also check if the oil pump screen is a bit dirty this also may restrict a ready flow in volume.

This screen is located at the bottom front of the right side cover.
To access this screen the right side cover needs to be removed.

Could be that at hi r's the centafugical force of the clutch is releasing oil and the pump is not keeping up with it because of some restriction or low oil level.
Even thought the pump is at the bottom of the engine like a subpump, it is worth checking out. Don't forget that this pump supplies the whole engine with lub.

1985 and assuming you never had the clutch apart in 12 years maybe it is time for some new clutch plates.

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Honda ATV Parts
Plug you info in and view the part breakdown for your machine
Look under
Right side cover
Crankcase & Pump
Clutch