[boris.h]79 GS 550 / 673cc project

[tkent02]

Also a $$$ 369 + $90 shipping NOS Marshall Deeptone gs550/650 4:1 - much more money than a new MAC ($350 shipped) but very nice. Probably not any difference in performance, but slight chance it has more cornering clearance if you run your tires to the edge and scrape your foot pegs

OK, if the Marshall is made to fit the 550 too it has the small diameter pipes for the 550 and must use spacers for the 650, I want the larger 650 diameter pipes. I'll be looking at GSXR pipes, but the pipe comes off the head a lot more vertically than the exhaust ports on our heads. Might take a lot of work to make it fit.

[Chuck78]

You could take the GSXR exhaust and the gs650 or 550 exhaust both to an automotive exhaust shop, and have them match the bends on the 550 for the GSXR 600 pipe

[tkent02]

That might be an excellent idea...

[boris.h]

Hello!
Today I'll receive # 152.5 mikuni main jets. I think I'll be close. The bike sputtered a lot before 4000 rpm, but waked up past 4000 rpm even I was way too lean with 142.5 mains.

[tkent02]

I'm going to 165s. Still a tad lean.

[boris.h]

Tkent, thanks. When you say 165, is it the mikuni size or the dynojet size?

[tkent02]

Tkent, thanks. When you say 165, is it the mikuni size or the dynojet size?

Mikuni .

[boris.h]

ok, little update: first time I got the bike running almost perfectly!

1552.5 mains
adjustable needles (yes I have!) on the last notch (the richest)
fuel screw adjusted to get a perfect color on the spark plugs!
Idle adjusted to 1000 / 1100 rpm.

When I bliped the throttle, no hole, no strange behaviour.... the bike accelerates smoothly...
About the main jets, I actually am almost ok, but I think it would be a good think if I go to 155 / 157.5, or 160 (I agree with you tkent02, it can accept 160 mains) and going back to one notch on the needles.

the bike runs ok, but I have some white fume, maybe burned oil at the exhaust... I put on this engine viton valve seals, I do not think if I did a good thing...

[boris.h]

[boris.h]

ordered today one pair of 157.5 and one pair of 160 mikuni main jets. This afternoon I will make some plug shops with the 152.5 mains. But I am close. If I can get more power and a wider power band (I found a flat spot between 2500 and 5000 rpm at wot, but after 5000 rpm the bike really wakes up)

[boris.h]

Yup
mikunis 160 mains for #2 and #3 carb, # 157.5 for the first and the fourth
Needles still at the last notch
The bike started properly last night. Will have a try soon

[boris.h]

Ok, Some news here...
I made 100 / 120km with the bike. I lost a lot of time because I have oil leak issues on the 4th cylinder. Before speaking of that issue, I would make a feedback about jetting:
main jets 160 / 162.5 / 162.5 / 160
needles on the last notch
diaphragm springs cut (2 rings)

full 4/1 bandit header and open muffler
velocity stacks on bs32 carbs
Full ported head, oem valves but grinded angles to increase the flow and air / fuel velocity

This set works hard, no bog, nothing, I drove it very easy...

I also synchronised the carbs but I had, after, an issue with my homemade rubber boots. I do not want anymore to put those because I can not trust in that boots. So I took oem boots and started to mill them to increase the inside diameter. Then I'll be able to clamp the carbs with more strengh.

OK, with that, but, in last but not the least: the oil leak issue on the #4 cylinder.
I made "only" 100km with the bike so I assume the engine is not still full broken in.

The symptoms:
- wet black plug
- white / grey smoke, the more is when startup, descelerating, and idle but not a lot now. When I am full throttle or cruising, no smoke. (so I assume the issue is when throttle is closed and when there is a lot of "sucking pressure" in the cylinder...
- oil going out from the interface between the exhaust header and the head, where there are exhaust seals..... The oil runs all along the head. there is burned oil and not burned oil that leak from there.

I thought about a ring issue.
- disassembled the cylinder and controled the rings, rings gap, angular position, nothing found...
- disassembled the head, inspected the valves, valves stem seals (I had viton new ones. I had the leak. Remplaced them by suzuki oem ones, nothing changed). The valves are brand new ones...
- checked and torqued the head again: nothing changed.

This Weekend I suspected this , when I saw the burned and not burned oil mixing all along the cylinder block: Could it be the threaded holes that would leak? If that holes are drilled too far they are on the head oil holes for lubrication.
Why not? I put 35 / 40mm long screws on them because the threaded holes are not in good state.

Waiting for the boots, I put some loctite sealant on the screws to see if there is any decreasing of oil along the head.

[boris.h]

Ok so after 3 months having disassembled all the head to get new valve guides the bike started again tonight... old gazoline in the fuel tank, which was almost empty. The bike started and idled. Not so bad but she needs more new fuel. Happy to hear it again

[Avinesh]

Love the thread bud!!! Thank you

[boris.h]

Thanks a lot!
For the little history the guy who replaced the valve guides had to work on the valve seats too... finally, to be able to put oem shims I had to grind the valves, until the valve stem was at the same height with the retainers... first start, it was a bit hot but ok without any bad noise