Project 74 GT550

[Allan k]

How do you take the forks apart? I have trouble getting the inner tubes out of the outer legs.

And the damper inside is also loosened But won't come out either.

[r3tro74]

How do you take the forks apart? I have trouble getting the inner tubes out of the outer legs.

And the damper inside is also loosened But won't come out either.

I removed the allen bolt that goes up through the bottom with a 3/8 air impact gun. I don't think that part even needs to come out because on this particular style there was not a seal on it. My Clymer manual states to tighten this bolt down with the fork assembled without the spring and fully compressed, I assume this centers everything.I used the air impact to snug it up because the whole thing just wants to spin around, once it "caught" I tightened it down with a ratchet.

To remove the uppers from the lowers, I took off the upper nut, removed the spring ,and the big snap ring on top of the seal. I held the lower in one hand and the upper in the other and compressed the fork allthe way and extended it forcefully a few times. This action caused metal washer, seal and upper sleeve (kind of looks like an upside down tophat) to pop out and the whole thing came apart. To get the seal back in, I used a 3' piece of pipe I found that fit over the upper for a seal driver. Be careful not to mangle up the snap ring groove. There is another thread "Please help ID some forks " that had a better picture of my internals.

I don't have a factory service manual and apparently these forks are different from a more common type so I pretty much just tore into it and made it up as I want. This may or may not have been the way to do it.

[r3tro74]

The frame was degreased with oven cleaner, power washed off at the carwash, and dried hanging in front of the heater. Sprayed primer today, hopefully sand and paint tomorrow.

[r3tro74]

More progress. The frame is painted with the front head set and rear swing arm/shocks installed. The rear swing arm is torqued down to specs from the oldjapanesebikes.com web site- Thanks for the information!!
The wheels are disasembled and I am working on cleaning them up. I may just paint the spokes black. I have new tires ordered and they should be here later this week. I want to get the wheels back together and back on the frame with the forks before taking more stuff apart- like the rest of the engine. I am running out of room to pile up parts.
My normal work schedule is going to be taking all my time for the next 6 weeks so the bike work is going to slow down a bit. Ill just have to whittle away a little bit at a time.

[r3tro74]

I have the wheels cleaned up and back together. Taking "before" pictures and measurments was helpful. I followed the directions here: http://www.webbikeworld.com/motorcycle- ... ke-wheels/" onclick="window.open(this.href);return false;

I have Brdigestone S11 120/90/18 rear and 90/90/19 front. The rear tire clears the brake stay, but not by much.
I read on an older post some one was questioning if these tires are still in production. The date codes are 1711, and 4111. These tires were made last year. Got them reasonably priced from : http://www.chaparral-racing.com/Product ... -0220.aspx" onclick="window.open(this.href);return false;

[r3tro74]

Wheels back on the frame.

I am "playing" with rotating the forks and moving the front brake to the left side. The fork hose bracket still seems to work OK. 2 potential problems are the fork oil drain screws now are on the UP side of the forks and I'll have to hold the brake caliper up in the air to bleed due to the position of the bleeder screw.

I just don't like the looks of the caliper pearched up on top.

[r3tro74]

Thanks to Coyote's description of a friction fit nylon insert on another thread, I made up an dial indicator attachment for setting the ignition timing by knocking the porcelain out of an old sparkplug and found a couple of o rings that hold the base of the dial indicator securely inside.

[r3tro74]

I wanted a café seat, but did not want to remove any of the original seat mounting brackets from the frame. I purchased the Road Race 3 from Hotwing Glass. I had to cut some notches to clear the brackets and trim a little off the front. The seat now drops down over the frame rails and is centered. The style of the seat cover hides the cutouts. I’d like to have the option to swap out to the original seat once in a while if the wife wants to go.
Also after swapping the forks/brake/fender every which way, I decided the stock arrangement was best. I did flip the headlight mounting ears side to side to lower the headlight a little and plan to flip the speedo bracket as discussed in another thread.

[H2RICK]

Taking shape nicely, r3tro !!!
It'll be interesting to hear what those Jemcos sound like.
You DO intend on showing us a short vid with full sound, don't you ??

[Coyote]

OK. 2 potential problems are the fork oil drain screws now are on the UP side of the forks and I'll have to hold the brake caliper up in the air to bleed due to the position of the bleeder screw

I bled both my front brakes with a Mighty-Vac with no problems. As far as the drain holes facing north, who cares? How often do you use those? You can't really get all the old oil out without removing the forks and manually draining them anyway.

[r3tro74]

Taking shape nicely, r3tro !!!
It'll be interesting to hear what those Jemcos sound like.
You DO intend on showing us a short vid with full sound, don't you ??

Thanks.
Yeah, I'm interested to hear how they sound, too. This is the only 2 stroke street bike I've ever even seen in person.

[r3tro74]

OK. 2 potential problems are the fork oil drain screws now are on the UP side of the forks and I'll have to hold the brake caliper up in the air to bleed due to the position of the bleeder screw

I bled both my front brakes with a Mighty-Vac with no problems. As far as the drain holes facing north, who cares? How often do you use those? You can't really get all the old oil out without removing the forks and manually draining them anyway.

Thank you for your replies on the brake set up on RedZone. The fork rotation scheme is from when I was originally planning on eliminating the front fender and running the bike stripped down of “unnecessary” components. I had a change of heart after looking at a pile of stock parts that I was gong to carefully pack away to someday restore the bike to original. I think the front chrome “grandpa” fender with all its braces and brackets is actually kinda cool, and that original air box with its chrome sides has some pretty large filters that probably have more surface area than the pod filters. So in the interest of preservation (and actually getting this thing DONE so I can ride it this year), the only changes at this time are going to be seat, bars, exhaust.

[r3tro74]

The engine is back in place with updated clutch assembly installed- THANKS Jabcb for making me aware of the clutch update! I finished polishing the engine covers as good as they are going to get. Poilshing is not that much fun, on a scale of 1 to 10 it pretty much sucks.
Started working on the carbs. I am confused about the jet part numbers. I believe the main jet part prefix #is N100 604, the pilot jet like the ones that came out of my carbs looks like prefix# VM22 210. These are VM28 carbs right? why the "VM22" in the part #?

[H2RICK]

This is the only 2 stroke street bike I've ever even seen in person.

That's a sad commentary on how governments can force us into the "behaviour/choices" that they want us to exhibit/make.
Yes, certainly something had to be done to lower smog production in major cities around the world....
but in the grand scheme of things the miniscule amount of pollution from ALL the two stroke motorcycles ever built pales in comparison to the pollution generated by a modest fleet of heavy duty truck diesel engines of the same era.

why the "VM22" in the part #?

A WAG says that Mikuni, like a lot of Japanese manufacturers, began their part numbers with a designator showing the first model that that particular part was used on. So, that style of pilot jet
was PROBABLY first used on a VM22 carb when they had made the changeover to ISO threads in 1966/67/68. They may have also redesigned the actual jet configuration itself somewhat at that time as well.

My .02 worth.....

[r3tro74]

This is the only 2 stroke street bike I've ever even seen in person.

That's a sad commentary on how governments can force us into the "behaviour/choices" that they want us to exhibit/make.
Yes, certainly something had to be done to lower smog production in major cities around the world....
but in the grand scheme of things the miniscule amount of pollution from ALL the two stroke motorcycles ever built pales in comparison to the pollution generated by a modest fleet of heavy duty truck diesel engines of the same era.

why the "VM22" in the part #?

A WAG says that Mikuni, like a lot of Japanese manufacturers, began their part numbers with a designator showing the first model that that particular part was used on. So, that style of pilot jet
was PROBABLY first used on a VM22 carb when they had made the changeover to ISO threads in 1966/67/68. They may have also redesigned the actual jet configuration itself somewhat at that time as well.

My .02 worth.....

Yeah, It must be that the 4 strokes are more efficient? I used to think the ban to keep 2 strokes off of the roads was due to the gas and oil mix. Untill I had a look at a Detroit Diesel V16. I would not have guessed it was a 2 stroke with the superchargers, oil pan, and valve covers. So much for thinking a 2 stroke needs an oil mix it the fuel.

Thanks for the info, I ended up stopping at a local "mom and pop" dirt bike store- MX Parts Now. http://mxpartsnow.com/" onclick="window.open(this.href);return false;
He had an asortment of jets. etc and helped me match up some replacements, The pilot jets do start with VM22. The float needle and seats start with VM26. all in my VM28 carbs so your explination makes sense. I'm pleased to find someone with an assortment if jets to match up. Sounds like I'll be lucky to pick the right size the first time anyway.