1986 Yamaha RZ350, Canadian Model

OJ

Member
Carbs cleaned, and I'm kicking myself for not getting ultrasound cleaner before. I'm also kicking myself for not taking pictures of what I took off the bike as I have a brass fitting on the right carb, that has a line running from it, but I don't know where the darn line needs to go. The brass fitting is on the left side (inside) of the right carb and there is no obvious place for the line to run to. Anybody have advice on fuel line routing?
 

OJ

Member
The carbs are not stock, but I found out the line is for petcock vacuum.

I’m freezing my ass in my uninsulated garage. I thought I had the carbs setup the right way, but it doesn’t look like it. The bike runs 1-2 seconds when I squirt 10-20ml of fuel in the cylinder and kick it over. Just enough to get some 2T smell in my garage. It seems that the carbs are not feeding fuel, or not enough fuel.

the photos show how I have my lines run. I hope somebody could give me some tips.
 

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OJ

Member
Well, this is bit embarassing, and hasn’t happened before (yes it has), but I didn’t prime the empty carbs and that’s why she didn’t want to start. A whole lot of assing around in a cold garage for something similar to ”do you have it plugged in?”
 

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OJ

Member
So now we know the bike runs. I called the previous owner today, as he is bit of a walking motorcycle encyclopedia and all the shop manuals put together. Or at least he is the most knowledgeable motorcycle guy I personally know, and under normal circumstances, I would be getting the info at out moto club shop nights. I have a list of things to do, and some instructions on how to do them. Starting from carb sync, then oil pump adjust, moving to cleaning the baffles, to likely replacing the outer crank seals and finally rebuilding the water pump.

I did order an ebay nose fairing and windshield for the bike. The fairing should be here early June, so that’s my target date to get the bike on the road.

EDIT: I think I’ll also rebuild the master cylinders and replace the lines. Don’t want to run out of stop.

And bit of off topic guest star update. I installed a little 2.5mm aluminum disc under the fuel pump diaphragm to reduce the fuel squirt from the FCR MX carb. Seems to help as the bike is easier to start (it’s a real b**ch otherwise especially when hot) and throttle response seems much snappier. I need to test ride next weekend to truly test it out.
 
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OJ

Member
Right now I'm washing all the dishes for the second time, baking sour dough bread, vacuuming just in case, and doing home schooling tasks with the kids. Reason for this is that I've ordered all my "consumables" for both of my bikes and the cost is what it is.

I would also like to pay this suspension guy to do my forks on my KTM. C$100 material + me doing it for the first time or C$350 somebody who knows these things. I'll wash the floors while I'm at it, but should I maybe wash the windows too?

Plus, we're in this restricted form of being and there's #$%& snow on the ground!!!
 

OJ

Member
Things have improved, I should have the consumables etc. this week, so I can proceed with working on the RZ. Don't want to start tearing it open before I have all the seals and gaskets to put it back together. It's also warm(er) so I can work in the garage.

Took my KTM for a nice 2 hour trail ride yesterday. That little shim in the fuel pump makes a world of difference. I couldn't believe the lack of stalls and being able to start it hot on 1-2 kicks. The valve cover middle bolt is leaking a bit of oil, but otherwise no issues. Will take the forks to suspension guy today to get them sorted out.
 

OJ

Member
Jetting question. Since the bike has Mikuni Power Jet carbs, I have hard time finding info on jetting as the jetting is different from regular Mikuni and jetting information is hard to find. Currently the bike has 160 main and 27.5 pilots. Stock airbox and DG pipes. I intend to ride the bike on the street and would like to maybe err on the rich side even if it would cost some hp. Do the jets seems about right or should I go bit bigger?
 

OJ

Member
I found some jetting advice. Powerjets are apparently 60 and 65, so to get to same as regular carb 240-250 main jet, I would need to up my main jet to 185-190. I was also adviced to use 27.5 pilot or bigger. So my thinking right now is that I should probably get 185 and 190 main jets and 30 and 32.5 pilots and start with the larger ones.
 
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OJ

Member
I had an error in the pilot jet sizes in the above post. I edited the original post so there's no info there. I did order the jets based on the correct info.

I took the covers off yesterday to get to the crank seals. Looks like the clutch plates and springs are not OEM, so I'll assume they're better/upgraded. Will give them a little sand paper treatment before putting them back. Figured I'll clean the oil and water pumps while I'm in there.

Some problems on KTM front. I took the forks to a suspension guy. He just texted me this morning advising me that the closed chamber cartridge is damaged :eek::eek::eek:. He's getting a quote for parts, and I really hope only some parts need to be replaced instead of the whole cartridge unit. I did a brief google search on those cartridges, and let me say it was hair raising google search. Some upgrade cartridges cost much more than what I have spent on that bike so far, including the purchase price of the bike itself.
 

OJ

Member
So, I listened to somebody, who claimed that you can replace the crank seals with the engine in the frame. That seems bit sketchy, as applying any treebond to seal the cases seems pretty darn tricky if the engine is in the frame, and new seals would do F-all if the cases would leak. Now I'm trying to decide between just running the bike for the summer with the old seals or pulling the engine and replacing the seals on the bench.

The KTM forks repair didn't turn out as ugly as I was afraid, but plenty expensive in any case. Might even get the forks back this week.
 

CarbsAndCylinders

Careful With That Axe Eugene
So, I listened to somebody, who claimed that you can replace the crank seals with the engine in the frame. That seems bit sketchy, as applying any treebond to seal the cases seems pretty darn tricky if the engine is in the frame, and new seals would do F-all if the cases would leak. Now I'm trying to decide between just running the bike for the summer with the old seals or pulling the engine and replacing the seals on the bench.

The KTM forks repair didn't turn out as ugly as I was afraid, but plenty expensive in any case. Might even get the forks back this week.
I know that you can replace the T/GT500 outer seals without splitting the cases. You can't replace the labyrinth seals that way but from what I have been told they do not usually need replacing. You could replace the outer seals and do a leak down test to check them afterward.
 

teazer

Well-Known Member
DTT BOTM WINNER
You cannot safely replace crank seals without stripping the whole motor on any bike. Early yamaha twins had seals with smooth outers and they changed that with the RD250 (air cooled) series. The cranks seals on an RZ have a rib around the outside to stop them moving.

What I'd recommend is doing a leakdown test. There are some reasonably priced leakdown set ups available and plugs for the exhaust or inlet are available from your local hardware store. On a Yamaha twin you have to block off both sides at once because the lab seal allows air to "leak" from one side to the other.

A leakdown test will show you whether there is a significant leak that should be repaired or if it's good to go. Do it while the side covers are off.

Interestingly enough my 85RZ350 (US model) has different carbs with linked throttle and no power jets.
 

OJ

Member
Would one of those cheap chinese $100 testers work reliably enough if I connect it to one spark plug hole and plug everything else? It feels like I’m throwing fist fulls of $100 bills at various things right now and don’t really want to spend much more on anything.

How about the ”nature” of those seals? If the bike has been sitting for 10 years for example, could it test OK leak down, but have seals leaking after the first time you put any pressure on it?

just thinking seal replacement might be the lowest cost way to get some peace of mind. Maybe not the least labor intensive.

Also, what would be the best to block the intake and exhaust? I can’t really picture that in my tired head right now.
 
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teazer

Well-Known Member
DTT BOTM WINNER

You can get those from your local hardware or Auto store.


https://www.amazon.com/Motion-Pro-08-0071-2-Stroke-Tester/dp/B000GUYSQG is what I use but I didn't have to pay for it or else I wouldn't have it....



Do not be confused by Automotive leakdown testers which operate at 100 psi. That would blow out your seals. You are looking for teh bottom end to hold around 5-6psi for 5-6 minutes with no discernable loss.

As to the crank seals, I always prefer to replace thm on any motor I build but others swear that filling the crankcases with diesel and turning the motor over a few times each day for a few days and then drain the cases supposedly is enough to rejuvenate old seals. You have to drain it back out or have a vacuum pump to pull it out.
 

CarbsAndCylinders

Careful With That Axe Eugene
You cannot safely replace crank seals without stripping the whole motor on any bike. Early yamaha twins had seals with smooth outers and they changed that with the RD250 (air cooled) series. The cranks seals on an RZ have a rib around the outside to stop them moving.

What I'd recommend is doing a leakdown test. There are some reasonably priced leakdown set ups available and plugs for the exhaust or inlet are available from your local hardware store. On a Yamaha twin you have to block off both sides at once because the lab seal allows air to "leak" from one side to the other.

A leakdown test will show you whether there is a significant leak that should be repaired or if it's good to go. Do it while the side covers are off.

Interestingly enough my 85RZ350 (US model) has different carbs with linked throttle and no power jets.

Teazer knows a lot more than I do, take his advice.
 

OJ

Member
Thanks guys for excellent info.

Looks like I'll try one of those DIY leak down testers. Have 0-15 psi gauge already, so cost shouldn't kill me.

Filling the cases with diesel fuel doesn't sound like something I want to try.
 

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