GT550 2 holed pistons

[Coyote]

Nakasyl cylinders were never provided on the American shores. The were used on the bikes throughout Europe. That coating is similar to hard chrome. The only chance that yours have that coating is if the bike was imported from Europe. Besides that, I don't believe it was used anywhere on the early models. Someone would have to correct if I'm wrong, but I think it was just 75 - 77.

[crazyeights]

Vintageman-I looked at the needle jets and they were partially blocked throughout. I haven't got around to cleaning the carbs yet. Did you put aftermarket or OEM pistons in your 550?

My theory is that the bike sat for a while then someone poorly cleaned the carbs. Then they ran it until it blew the pistons. But I could be wrong- I still have to check many more things.
I haven't checked the timing yet so I don't know if it was a contributing factor.
Thanks to everyone for the ideas

[rngdng]

You can order the pistons from Bike Bandit, and others. Once you look up the part numbers, any Suzuki dealer can order them for you.



Lane

[Vintageman]

Vintageman-I looked at the needle jets and they were partially blocked throughout. I haven't got around to cleaning the carbs yet. Did you put aftermarket or OEM pistons in your 550? My theory is that the bike sat for a while then someone poorly cleaned the carbs. Then they ran it until it blew the pistons. But I could be wrong- I still have to check many more things.

I used OEM. They are obsolete from dealer I think and getting rare to find (welcome to the darker side of owning vintage)

I think the carbs got a little more dirty each year and leaned out. The reason they are more gummed up now is from setting probably.


I have few sets of early GT550 carbs and none of the needle jets meet my standards (did I say welcome to the darker side of owning vintage?)

As simple seal check, once jugs are off you can fill one side of the crankcase at a time with fuel/mix (whatever) and see if it leaks down.

[Coyote]

As simple seal check, once jugs are off you can fill one side of the crankcase at a time with fuel/mix (whatever) and see if it leaks down.

That's how I did mine with help from TZ. I pulled all the SRIS fittings and replaced them with plugs. Filled the left crank chamber brim full using kerosene and waited a minimum of 24 hours. No leaks on the left outer seal. Then I pulled the center SRIS plug to see if any kerosene had bled over to that side. Repeated all the way across and everything proved to be fine. Took about a week to do it as there is a lot of waiting time.
I realize this is probably not as effective as a leak down test. But it's hard to do a leak down test when the cylinders are off

[GTandcbr]

Just to clarify the jet situation I have exactly the same bike as you and have replaced all the jets with new parts from reiners' and all have the round needle jet into the hex as your do. I have done 10,000 miles this year with no problems.

[crazyeights]

Sorry for the long delay. I decided to get a set of used stock bore pistons because my cylinders are in good shape. I have a problem with my SRIS lines being brittle. I sourced a place for some new ones. Are they easy to install? I think I'm going to start a new thread on the rest of the project soon. Thanks for the help

[Coyote]

There are 6 needed clips that slide on the hoses at installation Once the line is over the barb, the clip slides over the joint. A few are hard to get at but doable.. I put all new lines and clips on my now sold cafe.

[Alan H]

For SRIS lines I've just used clear plastic flexi tube and wound copper wire around the end where the pipes go onto the spigots. Been OK for over a year and about 2500 miles.

[crazyeights]

I started the kerosine crank seal test yesterday morning. The camber seems to have it all there. The problem I'm having is getting the valves out. How do you get the SRIS valves out? Thanks in advance.

[Coyote]

The early valves were a press fit. Turning them should pop em loose.. Be careful with those, I'm sure they are NLA. The later screw in are available but I've never seen the press in type. I don't know because I've never seen an early case, but there may be enough meat to tap for the later style. They are an 8mm thread so the hole would have to be 7mm or smaller.