Triumph Rat Motorcycle Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
56 Posts
Discussion Starter #1
Just finished the valve adjustment at 24,000 miles using propforwards excellent explanation (& the haynes manual) I used a home made locking pin to secure the backlash gear and took the camshafts off one at a time (as an extra insurance against upsetting the timing). 1st shaft back on with the new shims - the 2nd (exhaust) shaft was loosened a wee bit (and quickly tightened up) before the securing pin quickly went in. Long story short - the exhaust side backlash gear is snug against the drive gear as it should be. The intake side has 0.3mm gap between the drive (cam) gear sprocket and backlash gear sprocket but otherwise all teeth etc aligned. The circlips on both look to be sat in identical and the engine turns over fine by hand - is this an issue to consider before I button it up and start the engine ? whew
 

·
Registered
Joined
·
8,872 Posts
I would see if you can get the 2 gears to slide together theres a wave washer that should hold them together,the back lash gear should sile on the cam if it does not slide something is wrong
 

·
Moderator
Joined
·
29,948 Posts
That sounds like they are not quite assembled right. I would defnitely pull that camshaft back off and get the backlash gear snug against the main gear.

As Mike says, the backlash gear should be able to rotate against main cam gear.
 

·
Registered
Joined
·
493 Posts
Alignment pins

If the alignment pins that fit between the holes in the cylinder head and the valve cam holder cap things are in place when re-assembling, it will be impossible to have more clearance than there was before it was disassembled. Of course that is assuming that the valve cams and the holders are being put back into the same place where they came out. :eek: They are numbered and have directional arrows SO even if all of the parts were just thrown into a box when disassembled it should still be possible to easily re-arrange them correctly
 

·
Registered
Joined
·
56 Posts
Discussion Starter #6 (Edited)
All parts reassembled as before.
I think the loosening off of the cap bolts (maybe one turn) and retightening before remembering to put the locking pin in has allowed the tension spring to push the backlash gear out a fraction from the cam gear flattening the wave washer a bit (the circlip is still on) hence the 0.3mm gap between the gears. A flat blade screw driver shows the 2 gears moving independently (maybe a half millimetre movement in the tensioned gear)
I'm going to pull the intake camshaft and reseat the backlash gear tight against the cam gear / maybe replace that wave washer too.
 

·
Registered
Joined
·
1,576 Posts
cam gears

Stewart,

I had to fit the backlash gear completely when I changed the inlet cam a while back, the new cam had none of the backlash gear parts on it. The 'spring' behind it is just a big circlip, but it has quite a lot of tension on it when the backlash gear is in the correct place. The smaller hole in the backlash gear has to be concentric with the bigger hole in the cam gear, when it's all back together correctly. Keek through from the lhs now and see if this is the case.

It's possible if you've lost the pre-tension on a backlash gear on re-assembly, meaning that it's one tooth back from where it should be. I had to tension mine up first anyway, because it was assembled from the individual parts. I used a 3mm ball ended allen key as a lever through the holes, to advance the backlash gear into the correct position. It's then easy enough to plop the tensioned assembly into place and remove the key.

Where are you anyway? If you're not too far from Ayr I can nip round and show you what I mean, it's easier than trying to explain it verbally.


 

·
Registered
Joined
·
56 Posts
Discussion Starter #8
Cheers Johny thats all useful stuff to think about and good for future reference too no doubt.

I got my DIY stepped locking pin pushed through the camshaft gear and backlash gear before i lifted the assembly off so I know those holes are sitting concentric to each other - I'll have another look at it bolted down tho. The backlash gear (as fitted) has the tension in it - problem is I can slide a 0.3 feeler gauge down between the two gear wheels (not possible on the exhaust side camshaft) and I suspect these two gears should be tight together. I'll post what i found when i reassemble them.
I'm in Fife btw - a bit of a haul over from Ayr but thanks for the offer.
 

·
Registered
Joined
·
56 Posts
Discussion Starter #9
Well after the NY I pulled the exhaust camshaft off again and dismantled the backlash gear using the Haynes pin and screwdriver method (fairly straightforward but 3rd hand required). The spring in there is chunky (like a 3mm thick circlip pushing between 2 opposing studs) The spring was sat where it should be so cam back in, turned the motor over a few times by hand and then fired it up. Runs as before but a wee bit noisier. Next 12,000 mile valve clearance job will be a breeze and a wee bit more learnt about the bike.
 
1 - 9 of 9 Posts
Top