Few questions

[stef]

Hi guys,

The zxr is sounding a bit ill so it's probably about time i did some work on it.

I've read the know how guide on valve clearances, that looks pretty easy so i'll be doing that myself.

What do i look for on followers and on the cam lobes as far as wear? Engines done about 36k miles so i should think some stuff must be worn.

Also, the cam chain sounds like a machine gun at idle, from what i've read the tensioners gone? It says to measure 20cm of the chain to see how worn it is, can i do this at the top when i take the rocker cover off for the valves?

I'm assuming the tensioner is a fairly easy job, cam chain doesn't take my fancy though. Have an L model, from what i've read i'll be needing to at least pivot the front of the engine down the frame.

I take it i can't just take the old off and thread the new one through then.

Is there anything else i should be looking at around this mileage? I don't see the point in doing the head gasket unless it goes really.

I guess i should change the wheel bearings etc as a matter of course as well?

The revs are hanging sometimes at ab out 2k when coming to a stop, I'm guessing this means air leak, probably carb rubbers? Anyone know if i could seal them or sould i replace, assuming they are the problem.

Think thats about it, sorry its so long winded, like to know exactly what im doing before i pick up a spanner.

Cheers,
Stef

[zimm]

wear on followers/cams etc is a piece of piss to spot.. followers get a groove in them, basically, just compare all the followers, and all the lobes, some wont be worn, some will, if they all look the same, its all fine.

just change the camchain, they wear out, its just a fact of life, and measuring 1mm of wear over 20 links under a specified tension accurately is just.. well, just change it.

ive never had a tensioner actually fail*, just fit a new chain, and see how it sounds, it'll most likely be fine. Tensioner can be changed without disturbing any other engine internals at a later date if it needs doing.

engine can stay happily in the frame to change camchain, just align the crank, remove the cams, do your follower/lobe assesment, pull out the old chain, fit new one, and put the cams back in timing it all up as per the manual, this is all covered in other threads on here.

change the wheel bearings if there's play, kinda a waste of £40 (?) if there isnt.

rev's hanging is an air-leak or weak idle mixture, tweak the mixture screws a bit richer and see if that cures it, if not, pull the carbs off, clean the intake stubs up, smear (lightly) with silicon and re-fit the carbs, this should stop any leaks. If not, then re-do this but take the stubs off the head and use silicon to seal the stub/head surface as well as the stub/carb surface.





*well, ok, one .. on an early 1988 ZX-4 which uses a different tensioner with a ball-race clutch, instead of the toothed sprung bar. even then i didnt actually swap it out.

[zimm]

um, just thinking, if your bike is tapping like mad at idle its probably worn followers.. loose camchain is more of a rattle just after you release the throttle when blipping it.

valve clearances close up as time goes on due to a combination of valve stem stretch/valve seat recession so the lobes wear a groove in the followers as when the engine is hot (thermal expansion) there is no longer any clearance.. this means it's tappy as feck from cold at idle.

[stef]

Sounds about right zimm, cheers for the advice.

Was gonna get a shop to do it, but to be honest i prefer doing stuff myself anyway, i like learning!

Gotta finish off my other bike and get it sold, so i can do my garage up into a proper workshop, then i think i'll attempt this stuff.

I'll do the chain and tensioner anyway i think, i dont think they are very expensive? just like to do everything while i'm there anyway so i know i wont have to touch it again for a while.

Any idea how much followers would cost? i know shims are about 6 quid or something rediculous, so i'm guessing they arent cheap.

I guess i just have to hope the cams arent worn as well. Probably will be though lol. If they are, i heard Kent do cams.... had kent in my mini and that was fun. Good idea or should i just stick with standard? I guess theres Beet as well.

mmmmmm Beet.

EDIT*

Am i ok to ride the bike distances? Still goes like stink, but planning to go peterborough tomorrow as theres an open day at taz, bout 80 mile round trip i guess on the A1, will be pootling at about 6000 rpm for a while i guess.

It's not daily transport so even if it does go bang it wouldnt be a massive issue.

[zimm]

if it's worn the followers then they will wear QUICKLY as the hardened surface is V thin, and the material underneath is soft as fook, and yeh, they'll bugger the cams quite quickly too. So i wouldnt be riding it much distance like that..

if its the chain, how long has it been doing it ? cos IF it lets go, you may as well buy a new engine, the damage will be extensive.

as for cams, kent's regrind is meant to be good, but you need thicker shims (which arent readily available) the SP cams will work with shims within the normal range and they have a good profile (kent describe their cams as "a bit better than sp" lol), not sure about Beet, but i doubt they are toad... all of the above will probably cost as much if not more than a replacement engine. If you need cams, the best budget option is cams out of an H or an early L (pre L3?) as they are a smidge better (more duration or lift, . i forget which)

cradley wanted £50 for a tensioner last time i spoke to them .. maybe i misheard.. but im sure thats what they said.. i didnt buy one.

camchain was about £20, did the mrs' bike couple of weeks back and just the new chain cured all kinds of nasty ticky/tappy noises

dunno about followers.. i've got 3 scrap engines i pull stuff like that off as and when i need it

[parby81]

last tensioner i got (the early type) was £25 inc vat from cradleys

[zimm]

last tensioner i got (the early type) was £25 inc vat from cradleys

and its going in my H1 later this evening

[parby81]

Glad it got to you mate, just need to get myself one of the newer type ones now.

[stef]

Ah well, i'm a bit late as i did the trip anyway, and ragged it to hell there and back.

Still runs fine though. Karma will come round soon enough i guess

Irritating as ive got another bike to finish first, i guess i'll start stripping it apart at the weekend and then i wont be able to ride it!

Cheers for all the advice guys, will post up pics etc of stuff when ive got it all apart.

[stef]

Another question i thought of, where is the mixture screw for the carbs? can't seem to find it.

And the exhaust smells very rich, when i come to a stop after a rag i can smell unburnt fuel pretty badly.

So i guess richening it up isn't the best idea.

cheers