dominator engine rebuild

[Jessecollett]

hi all, i'm new to the forum and have a couple questions.
im in the middle of my first engine rebuild. a dominator (same engine as xr650l)
when i was removing the kick start shaft there was a circlip that i broke (it was on the shaft where the arrow is pointing at). my manual doesn't have anything about a kick start in it and on part fiches of the kick start there is no sign of the circlip. Any ideas?


and here is the diagram:

Google Image Result for http://images.cmsnl.com/img/partslists/kick-starter-spindle-nx500-dominator-1989-austria_bigecn9j41e__1500_739a.gif

also,
on the balancer shaft there are those two gear wheels. are their teeth supposed to line up? the photos in my manual are useless




and lastly, the bike has done 60,000km /40,000miles ish. all the bearings feel fine but would it be a good idea to replace them anyway? or is that unnecessary? i was thinking i'd just replace the crankshaft bearings as the manual said to replace them if they came out with the crankshaft instead of remaining in the crank cases. (which they did)

any help or opinions would be much appreciated, thanks

[navalarchitect]

I haven't worked on a Dominator engine but based on experience as an engineer and also as a regular amateur mechanic I would say:

(i) replace the circlip it was obviously intended - whatever the parts list says (presumably your model and the parts list aren't the same - there are often small year on year changes). Either get the circlip via a Honda dealer or simply take the shaft and old circlip to a bearing supplier and ask them for a replacement. There is a very high probability it is a standard size as Honda minimises its cost by using standard parts wherever possible.

(ii) Gear - I think it is meant to be offset. There will be some sort of spring loading mechanism between the two parts and the offset then keeps the gear in perfect mesh to reduce noise. (If it was meant to be in line they would make it in one piece).

(iii) Bearings - replacement depends on your finances and nerve. If I'm feeling rich I change them all, if not (or in my current case saving for a trip) I change any that obviously needs changing and then trust to luck. Bearings rarely fail except at huge mileages unless they are starved of oil so risks i think are reasonably low and i am currently following this philosophy on a KLR motor I'm rebuilding. Now the exceptions to this advice are (a) probably worth changing the bearings you mention - if Honda makes the recommendation it has been made for a reason and (b) carefully examine the output (countershaft bearing) and seriously consider changing it - being just behind the sprocket it takes high loads (especially if the chain is run over tight) and often gets muck in it past the seal (and definately change the seal).

For all the bearings and seals you are going to change take the old ones to the bearing shop - you will probably find at least some are standard sizes and they will be a lot cheaper (a quarter of the price) there than at the dealers. Only use the dealer for any specials.

Hope this helps and good luck.

[navalarchitect]

Item 13 looks like the circlip

[McCrankpin]

I had a look at the Honda workshop book for my XBR500. It has a kickstart, in the same engine as the 650s, but different in detail.
My kickstart shaft has a cam to operate the decompressor which doesn't appear on your parts diagram.

But as navalarchitect said, the circlip is No. 13 in your diagram. (There are two circlips in that area on my bike, one to hold the decompressor cam in place).

There's another picture that may be useful if you don't have it or haven't noticed it.
There are a couple of punch marks on the shaft and the ratchet to ensure they go back in the right place:




But once again, in the absence of that decompressor cam, your bike may not have the punchmarks. The ratchet may not need to be in a particular place without the cam.

Hope that helps rather than confuses!

I'm wondering why you're rebuilding. I have the XBR and a Dominator (same engine again), and neither engine has ever had a spanner anywhere near it (except regular oil and filter changes), and the XBR has 80,000 miles, the Dominator about 40,000. They have a good reputation for longevity.
Take care with the reassembly.

[McCrankpin]

Also had a look at the balancer shaft in my XBR500 manual. These photos may be useful.

The two gears will line up when you engage them with the crankshaft gear, but there are punch marks to align on each of the two balancer gears so they align with each other:







There are also springs between the two gears, if you separate them, they may pop out and disappear.... for ever.....



And more punchmarks when engaging the balancer gears with the crankshaft gear:






You probably guess from my previous post, I've no experience of looking inside these engines, am only taking info from the manual that I've never used. But have delved into many other Honda engines.
That's a nice situation, having the manual but never having had to use it over a reasonably long mileage.

Cheers.

[backofbeyond]

The balancer shaft twin gear is like that to stop backlash chattering in the linkage between the crank and the balancer. Without it there would be points in the cycle where the crank is "leading" and other points where the balancer was, eventually you'd be getting wear and noise.

If you've got the engine apart you might as well replace the mains if you can get them cheaply enough - from a bearing factors or the like. If they pulled out with the crank rather than staying in the cases I'd be looking more closely at the crankcases to see if the bearing outers have been turning and wearing the housing. If there's wear you can probably sort it out with loctite.

Like others I've never had to go that far into my XR version of the engine. Top end's been off a few times but I've never had to split the cases.

[Jessecollett]

thanks everyone, it all makes sense now.
i'm rebuilding mainly just to check it out for piece of mind on long trips probably to india first. there's always little problems that could get worse once you look closely. its was running pretty much fine before, gearshift shaft had snapped though which needed cases split to replace it.

[JonStobbs]

A good supplier in UK of bearings, seals, and even circlips is Simply Bearings Ltd ~ Oil Seals SKF FAG TIMKEN KOYO NTN NKE TRULOC Needle Rollers Taper Rollers Rod Ends Oilite Bushes Loose Balls O Rings Grease Plain Thrust and they do list engine-specific bearings too (some have a locating groove or shoulder). Very good service.

[teedee]

Hi,

I would replace the bearings while your in there, and that circlip will need replacing, as to the balance shaft it should be as shown in your picture, but you will need to align the gears to refit, just use a small nail in the holes and align the gear teeth this will make it easy to fit back without causing damage. You say the gear shaft snapped so i would check every bearing in the gearbox and make sure there's no metal fragments in there. I'm currently rebuilding my dommie engine with rebuilt crank and rebore and replacing anything i don't like the look of. The dommie engine is easy to rebuild but you might as well do it once rather than putting it back together and then finding something you should have replaced causing problems and having to do it again. Good luck on your trip!

Teedee

[Jessecollett]

ok thanks for all the help so far. im having trouble sourcing the right bearings though. i've taken the advice and been looking on simplybearings but i want to be sure im not ordering the wrong ones. (i'll get SKF's as they seem best quality?/most expensive)

-crank bearings, the bigger one has C3 stamped on it but the other doesn't. i'm aware C3 means theres more clearance around each ball to allow for heat expansion but surely both bearings are operating at the same heat?

-two of the transmission bearings and one of the camshaft bearings have letters after their bearing number (5205A, 6204U and 6904C) could any one tell me what these mean?

out of the 17 bearings throughout the whole engine, so far i've only found 6 that i can replace with ones from simply bearings. does any one have records of what bearings they've bought for a dommie engine?

and i'd have thought all the bearings in the engine would be C3 but only the one crank bearing i mentioned earlier has C3 stamped on it. ?

thanks for any more knowledge you're able to share

[McCrankpin]

This might help:

DirtBikeStore UK Ltd Engine Bearings Engine Bearings

As far as I know, where there's no suffix, the bearing is rated 'mid-way' which is close to the C3 rating.

[Jessecollett]

Originally Posted by McCrankpin

This might help:

DirtBikeStore UK Ltd Engine Bearings Engine Bearings

As far as I know, where there's no suffix, the bearing is rated 'mid-way' which is close to the C3 rating.

had a look but the suffixes i've got dont seem to be standard. thanks anyway.
i'm tempted to just get the whole lot from the dealer.
i could save about 100 quid if i get some from other bearing dealers but i'd rather not put the wrong bearings in my engine.

the other thing is the big end bearing, this slipped by me as its not on any parts fiche. i take it this bearing cant be changed (from reading various posts) which is a bit annoying as i'll have spent hundreds on changing all the others and have one old one in there

[backofbeyond]

Originally Posted by Jessecollett

the other thing is the big end bearing, this slipped by me as its not on any parts fiche. i take it this bearing cant be changed (from reading various posts) which is a bit annoying as i'll have spent hundreds on changing all the others and have one old one in there

From memory it's a roller bearing big end and as such it'll be rebuildable in the same way that two strokes are. Unfortunately it's not going to be as simple as the other bearings - you'll need some serious workshop equipment such as a hydraulic press to take it apart or you'll need to farm it out to somebody who has and knows what they're doing.

However, unless the bearing's got rusty or you've run it on battery acid instead of oil or something like that they do last. They have a decent oil supply - unlike a 2T that'll do 20-30k miles on whatever oil happens to fall on the bearing.

There will be wear limit info for the Dommie crank and it might be worth checking that first. For my XR600 engine, the manual gives these limits on three checkable items - crank runout - 0.1mm, conrod side clearance - 0.8mm max and big end radial clearance - 0.05mm. I'd be surprised if the Dommie crank is much different.

[Jessecollett]

Originally Posted by backofbeyond

There will be wear limit info for the Dommie crank and it might be worth checking that first. For my XR600 engine, the manual gives these limits on three checkable items - crank runout - 0.1mm, conrod side clearance - 0.8mm max and big end radial clearance - 0.05mm. I'd be surprised if the Dommie crank is much different.

yeah, im within the limits. to be honest i wouldnt be replacing all the bearings if i hadn't been so messy and got bits of grit, gasket and metal shavings everywhere and also cleaned the cases with a pressure washer and not dryed/oiled it after (rusty bearings). wont do that again

[Jessecollett]

could any one tell me which order piston rings go?
i've searched everywhere and cant find a real answer.
my manual says the beveled one goes in the middle but done of them are bevelled. (they are genuine hondas by the way)
the oil ring side rails and spacer is obvious but the other two aren't:
one is smaller and is black with a shiny silver edge, the larger one is black all over
thanks for any opinions