RF900 misfire

[headcase]

Hi!!


Just joined this forum, its hard to find others with an Rf900... so here goes, my problem.

2 probs.

When i rains my Rf900 misfires pretty bad. i hear its quite a common problem. i think water is getting in between the tank and the engine and down into the plugs? how do people fix this? was it a design fault or something that developed over time?

also... i have a knocking from my front suspension... not during normal riding but when i brake or when i go over serious bumps.. i checked the head bearings and I think they are ok. any ideas?

sorry if i have been a bit vague...

I am based in the UK but dont hold that against me

[riffer]

Gidday.

The RF900 is a shocker for misfiring in the rain. Here's the solution.

Whip the tank off and liberally apply Vaseline to the following areas:

1. Where the low tension wires attach to the coils.
2. the wire junction box behind the steering head
3. the tops of the spark plug leads where they enter the head of the motor - there is a kind of round cap on there which will let water down so it can collect in the spark plug recess. Also get an air compressor and clean out all that spark plug recess as well - there are water outlets which can get clogged up with road crud - make sure the spark plugs are in first - you don't want to get any of that crud in the motor.

Do these things and your RF will never misfire in the rain.

[riffer]

As for the knocking in the front suspension.

I don't think your forks are assembled properly. I once rebuilt my forks and in a fit of madness didn't loctite the catridge to the preload nut at the top of the fork. End result - when I wound the preload out to minimum the cartridge actually fell off and it made that exact same knocking noise.

Another thing it could be is that you've not assembled the forks correctly (or the person who last worked on them didn't) and the washer at the top of the bottom part of the fork is not in the right place. This can cause the catridge to move up and down when braking.

[riffer]

Check also that you've got the right pads in the calipers. If there's a bit of slop this could cause a problem too but my money's on the forks not being assembled right.

[ManDownUnder]

What riffer said re the water tightness of the RF. Yup - it's a well known problem to miss in the rain. It can be a real bitch sometimes...

Re knocking in the forks - I'd recheck the steering head bearings. Easy enough to do but you'll need one other person.

Side stand down, steering on full right lock and standing on the LH side of the bikegrab the handlebars and pull them towards you - lifting the front off the ground (the stand is plenty strong despite it being a tad heavy...)

Front brake on, and get your mate to grab the front wheel and push/pull it horizontally. Don't be shy - give it a good go. Any slack in there will result in that knocking you refer to.

If that ain't it - forks are your next stop. Inside them are a couple of bronze bushes that slide up and down the inside of fork tubes. I'll bet one of those is worn.