Is my clutch on the fritz?

[iranana]

Here the old gal is, bit of an old photo but you get the general idea! I'll one day replace the front mudguard (I believe it's off an RD400 Daytona Special) with the original chrome one if I feel so inclined. I think the white suits it though. That's good to know that Boysens require a change in jetting - I wasn't sure how much of a difference it would make but I'll keep that in mind In terms of the bent needles, I straightened them out of a sheet of glass as well as I could, so now there's maybe a .5mm bend. I'll replace them anyway, but I'm thinking the needle jet might be worn if the needle was running with a bend in it for a while...and that'll also be screwing up the jetting. I'll replace that too while I'm in there then!

This has been my first rebuild project and I've been a bit concerned about breaking the engine in. If my jetting is too lean or rich while I break the engine in, will this have a noticeable effect on the break in process? I've ridden 250km on it so far, it's not made any funny noises or felt at any point like it was going to seize or die on me. It's only now that I've ridden it for a while that I've noticed all of things that aren't right, I just hope I haven't messed up the break in process with possibly bad jetting. But ah well, it'll get another top end rebuild one day anyway. Gotta learn one way or another.

[F5 Dave]

Yeah they're a good looking bike. Too rich won't hurt it. Don't absolutely thrash it or lug it too much & you will be fine.

When you have the carbs out take emulsion tube out & look down it with a magnifying glass & bright light. Any ovalisation will pants the mixture. If it isn't ovalised then it won't be worn. Blow through the holes in the tube etc. Avoid poking wire through them as this can root them. Maybe plastic brush bristle. Try soaking & compressed air first. You will find where all the holes in carb lead & can be blown through.

[iranana]

I came across this just today: a cutaway view of a Mikuni VM28 Carb. Kinda cool. Here's a picture of one of my plugs too, just for reference. Been in there a while though, since the rebuild, actually. Just waiting on my carb kit to arrive... Realised it doesn't include the needle jet. How quickly would a needle jet wear with a bent needle? No idea how long it was running with a bent needle, so I best try and track down a couple of new ones...

[F5 Dave]

yup, shows most passages & how all comes apart. Simples. So you can pull out the needle jet (emulsion tube by another name) & eyeball it as stated above.


Sometimes you can learn something looking at the plug of a roadbike if you've been on a long trip, but the proper way is the race way & it involves holding it pinned for quite some time & pulling the clutch killing the engine & pulling the plug before it gets contaminated. If you have been running in riding it around then it will be dirty no doubt. So don't read too much into it, even though your eyes are tempted to say Rich, - the test method has invalidated the results.

[iranana]

Yeah the old plug chop method. I'm keen to do a few of these but the only place I can really think of is the motorway, unless I take a ride somewhere more rural. Don't want to get pinged blasting down the motorway full throttle, in top gear! Thank god it's Friday. Can start work on the carbs, will post after I've sorted em out I've developed a leak in a head gasket too. The gasket layer on the cylinder was damaged by some previous muppet owner who presumably hit the cylinder with a hammer or something trying to free it after a seizure. It has some small dents/impressions in it. I ground both the heads and cylinders down on a sheet of glass with valve grinding paste to remove any warp, but the impressions are quite deep and I figured I'd just see how it went. Apparently the best way to solve gasket leaks like this is to anneal the copper gasket (assuming it is a copper gasket, use a new one if not) by heating it till red hot and quenching it, and then use Permatex Ultra Black gasket maker just to help seal it, then torque it down a couple of ft-lb's more than spec. I'll give it a go and hopefully it does the trick! Otherwise I'll have to mill the cylinders Can't wait to have this bike up and running with no mechanical issues! Not the quickest thing around, but really nice to ride.

[F5 Dave]

My RD350B had copper ring gaskets & used to put them on the electric stove to get em red & drop in water & they would shed lots of dark oxidisation, or whatever copper gets.

Sometimes you can surface a bit with a new oilstone rubbed in figure 8 sort of pattern.

Not sure what temp spec Black gasket maker is but I've used Loctite Master Gasket on aircooled bikes & their Red Hi temp stuff is probably better still. Repco will have.

[actungbaby]

E will be CDI.

Don't know what has gotten into Akzle, I'd almost warrant that as helpful advice.


Start from the start, its an old bike & has been no doubt sitting for an age. Yam plates get pretty bite-y if left to sit. Cables can get knotchy & grabby so don't let out evenly sometimes. I'd pull the cable & oil it feeling how it operates unhindered. Pull the plates & clean them up rubbing them on the smoothest concrete you can find & then cleaning them off. Check basket for grooves on the basket.

A good carb clean, new plugs & replace that woebegotten airfilter before you adjust anything much. (try find another needle on internet with same number) look for airleaks (sometimes weeping oil) around reedblocks, inlet rubbers, behind flywheel & monitor gear oil for level dropping.

Clean out the mufflers, search internet for how to.

Yeehah.

Intresting read as i got ns 250 honda Guy told me dad build a bonfire put the exhust on the ashs heat it up burn of the oil inside hehe

I just taken of the one piston i have . another on its way for top cylinder but i my other piston shaged as got small gap above top pston ring groove is that heat damage

or designed to be that way . dont want put engine back togehter for melt blow up the engine

[iranana]

Intresting read as i got ns 250 honda Guy told me dad build a bonfire put the exhust on the ashs heat it up burn of the oil inside hehe

I just taken of the one piston i have . another on its way for top cylinder but i my other piston shaged as got small gap above top pston ring groove is that heat damage

or designed to be that way . dont want put engine back togehter for melt blow up the engine

I don't really know what you're trying to say, try and be clearer next time... Yeah you can burn off all the carbon and oil and crap in the exhausts by heating them up nice and hot. Generally, most of the gunk will just burn out over time if you jet the bike properly and ride the shit out of it occasionally. If you're talking about those little notches on the piston ring grooves, they're probably meant to be there. Usually on two strokes the ring groove has a little tang that stops the ring from rotating. Not sure why yours has a notch, maybe your rings have the tang on them instead.

[F5 Dave]

Don't sweat I've virtually never understood any of his posts. At least this one has some spaces between the sentences.

Surely he understands ring pegs, but who can tell? I always re-read my posts so I can see if I am making any sense.

Anyway back to your thread.

[iranana]

Oh yeah, so I got to work on that gasket leak in the weekend, but I've concluded I have to get the cylinder milled so I'm taking it into a machine shop this afternoon. It was too badly pitted to just patch up. I tried, it didn't work and if it did it wouldn't have been a permanent fix anyway. I've attached an image, it's a bit of a crap photo but it gives you an idea of the amount of damage. I also got to work on the carbs, I didn't really get very far on them as I was preoccupied with the head leak, and my carb kit didn't arrive this weekend like I thought it would.

Upon a quick inspection I found the needle jet to be visibly worn from the bent needle (has a groove running down the side of it) and the pilot jet is stock but the main jet isn't (can't remember what it was though). The carbs aren't all that dirty, but the gaskets look like they might be the old stock ones. Updates to come as my parts arrive and my cylinder is milled... I just realised that this thread was initially about my clutch. The clutch is improving on its own, actually. It might have been the fact that it was sitting around for so long that it got so bitey. I'll change my gearbox oil soon to see if any crap has gathered, but I'm thinking the clutch just needs use to free up.

[F5 Dave]

What the? how did it get like that? [reads back a few posts] why would he ball peen a gasket surface? Take off least possible. They will have been set up loose as a goose, but if you need to take off more than 0.5 you will be on 95 octane from now.


Shame about the needle jet but at least you know. Can you find one on the internerd? Those carbs used to be give away, but things have changed.

As I said in my first post the plates get Bitey which was a new word. My old RD50 would seize its plates fully together when left to sit & eventually would break & loosen up.

[iranana]

Oh yeah it was you that mentioned they get bitey. Do they become brittle and would bits of the plates be polluting the gearbox oil? I have no idea how the pitting really got there, it seems almost unbelievable someone would use that much force. There's a broken fin on one head and a broken fin on the opposite cylinder too... I can only guess they tried to pry them off with something... Makes me wonder whether the broken head and cylinder once went together as well.

I always put 95 in anyway, my RG ran better on it than 91 but it had higher compression I think. Maybe the RD would be better on 91... But yeah I've found that I can get double thickness head gaskets but I'll have to wait and see how much they have to take off. The thick gaskets are 0.04" thick.

I have indeed found another needle jet - I've been sourcing all of my parts from Yambits and so far things have been of good quality so hopefully the carb bits are too. I got a Mitaka piston kit from them too, as well as bearings and so forth. I've read varying things about Mitaka but I'll see how they go.

[F5 Dave]

Good stuff. I have heard that yambits have a bad rep for some parts on the RZ500/350 site hope yours are ok. Plates used have bit of copper that would weld together . Should stay together fine.