NC30 track bike not been used in 8-10yrs, where to start?

[28hodge]

Slowly im starting to get somewhere with this, tho work and motocross are slowing progress, i was wanting to get a trackday in by the end of the year but i may be pushing it now, still i'll see.

Ive rebuilt one caliper managed to score a set off ebay for £25 with braided lines and M/C, and they actually felt pretty good at the lever, still i wanna be sure im gonna stop, so i bought a seal kit for them from david silvers pulled them apart, i very nearly did myself with one piston tho and the compressor, kin ell they come out at some pace!!!!

So carb cleaner rags and compressor and cleaning time, not my fave job given my lack of patience for anything, managed to get one caliper sorted still got the next one to do this weekend.

ive also taken the rear hub apart regreased it all and put it back together, changed the front wheel bearings and fully serviced the forks after i got some vfr lowers to replace my cbr lowers.

I put 10w fork oil into them, this is purely going to be a road/race bike for ss400 would i have been better putting 15w oil in??? haynes manual said a 90mm gap but i put it @ 80mm air gap to stiffen it up a bit, now a bit worried i have done the wrong thing as my internals aint standard, the springs are not progressively wound and the holes in the damper rod are welded up as below!!





After that i need to try and get the bike running, this will decide if i will get a track day in this year or not, as its been stood i have no idea if it had any antifreeze in it, id doubt it to be honest!!! and we have just had 2 mega cold winters!!!! it could be stuffed!!

other than that im trying to figure out the way forward with the rear end, the shock is standard and i havent got the cash to buy a race shock, i was going to do the 10mm dogbone mod to raise the rear and stiffen the shock, but i have an 18" rear and dont wanna be getting stung for tyres all the time, so was thinking a vfr750 rear and hub mod with the 10mm dogbone mod and then use the 18" for wets.

That way i can get cheaper scrubs till a point in time when my riding hopefully demands fresh tyres. BUT will the 10mm dogbone mod be enough to raise the ride height on a 17" does it take it past a standard nc30 with 18" rear ride height as they are pretty low on ride height anyway from everything i read you want to raise the rear ride height from that of standard with the 18" rear.

Any pointers please?

Ta
Kurt

[CMSMJ1]

Quick response as I am on a conf call..lol

@ forks - smaller air gap = more rising rate - bt careful it is ont too small. Should be right.

Shock - you on the non remote res? they are shit...get rid.

RVF linkage = what you need and an RVF wheel - 750 wheels are big and heavy.

[28hodge]

Cheers for that.

Got the remote res so its a later shock thats been fitted as the bike is an 89 model and would have come with a non remote shock as standard.

Can only find one rvf wheel an its on flea bay, i'll keep searching and turn my attentions to the engine for a while as if thats a paper weight then i wont be needing a wheel for a while anyway.

[CMSMJ1]

drunkn munky has one i think?

[28hodge]

A Dymag from a evo blade wont work will it as its 6" wide, im right in thinking this aint I?? the best a NC30 will take is 5.25" isnt it??

Shame as there are two evo Dymags at not daft money on ebay.

[28hodge]

Well the engine isnt a paper weight, well the rear two cyclinders arent at least, they are running but idling real high, around the 4k mark!! cylinder 4 (Front Right as sat on bike) exhaust is getting warm, not hot, but it wont run on that cylinder, if i remove the leads from the front two cylinders the bike runs on the rear two but at 4k idle. if i then one of the rear leads, basically leaving it only running on one cylinder it idles better at about 2.5k still high though.

Thinking im getting an air leak?? bike is not using the vacuum pipe ive taken that off and done the hrc tap mod so checked that is all sealed and seems to be good, pulled the carbs off again and the rubbers look a bit distorted and maybe leaking so orderes some new rubbers.

Also when i cleaned all the carbs and split them to untrasonic them i was never really all that happy with 2 of the pilot jets so i ordered some new ones from Rick O.

Would the blocked pilots stop the bike firing on the front two cylinders?? im running it without the airbox and filter on, i know this will make the bike run rough but it will still run wouldnt it?

ive swapped the coils from the back to the front and thats made no difference, got good spark on all four plugs and they are wet, tried swapping hot plugs around to help but still not having it??

any more suggestions or handy hints?

[Cammo]

Thinking im getting an air leak?? pulled the carbs off again and the rubbers look a bit distorted and maybe leaking so orderes some new rubbers.

Yes sounds like an air leak, it can easily happen with old rubbers. You can check by spraying some easy start around the carb rubbers while it's running, any leak and the revs will rise.

Also when i cleaned all the carbs and split them to ultrasonic them i was never really all that happy with 2 of the pilot jets so i ordered some new ones from Rick O.

Would the blocked pilots stop the bike firing on the front two cylinders?? im running it without the airbox and filter on, i know this will make the bike run rough but it will still run wouldnt it?

I would have thought straight up that this issue sounds exactly like blocked carb passages after a bike has been sitting, though ultrasonic cleaning usually dislodges all the gunk. The carb idle passages are easily blocked with fuel residue.

It will run without an airbox and filter but they don't like to, and will probably manifest itself as other running issues. Best to put those bits back on to properly diagnose the problems, you'll be chasing the problem around in circles otherwise.

Pilot jets operate over the entire rev range, so yes, they will affect idle if blocked though it won't usually stop it firing some and I doubt this is the main cause of your problems. Might also be worth checking that the pilot screw o-rings are in decent condition and not affecting the pilot screw setting.

ive swapped the coils from the back to the front and thats made no difference, got good spark on all four plugs and they are wet, tried swapping hot plugs around to help but still not having it??

Wet plugs are never a good thing in an NC, a sign of flooding and sure to be trouble. Often these will spark outside of the bike but not under pressure in the cylinder. There might be a chance that the cylinders are so wet that the good plugs won't work in the front cylinders. leave the plugs out overnight to dry out the cylinders. Unfortunately the only way to rule out bad plugs is to buy (or borrow!) new plugs. Spark plug issues and their fragility has had many a person scratching their heads on these bikes! I'm assuming that you know not to flood the bike when starting (full choke, NO throttle until warm).

If all else fails I would try borrowing another set of carbs to rule any issues with them out. After sitting for so long there are sure to be issues with them, perhaps even after ultrasonic cleaning.

With elimination of each potential cause I don't think this will be a big problem to resolve, it's just that you have more than one issue going on here.

[28hodge]

Cheers cammo, hoping when i get the new rubbers the high idle on the rear cylinders, if not then i wont worry about them just yet till i get all four firing then i'll get them running right. didnt have any carb cleaner to hand when i had it up and running but im pretty sure its a air leak due to the old rubbers.

I'll get the airbox back on it before i try again but im really just intrested in getting all four cylinders up and firing regardless as to how rough it runs, got 8 plugs to go at, im trying not to soak them and if i do i try and put them into the running rear two cylinders to dry them out clean them up.

Pilot air screw o rings not checked or looked out so will bear that in mind, all the pilots have turned up from Rick O but i work away from home so wont have chance to do much till sat.

Cheers for the guidence cammo.

[Neosophist]

pilot jetting isn't usually that bad, it's the idle circuitary.

If you look by the butterflys on the carbs you'll see 3 tiny holes, these need to be clean and clear... some strong compressed air and carb cleaner can help

[mattiec321]

pilot jetting isn't usually that bad, it's the idle circuitary.

If you look by the butterflys on the carbs you'll see 3 tiny holes, these need to be clean and clear... some strong compressed air and carb cleaner can help

Sorry guys to hijack the thread but where exactly? under the butterfly I can see two holes. Once from the choke and one from the floats.

Sorry for being an ass.