An FJ600 update and ?

Hey,
Well, I cleaned the carbs and adjusted some of the shims with some that I had, one was so tight it couldn't be measured. Pulled that shim and put a smaller one in and re-measured it.
The bike was up and running and idling with just a bench sync. Not going forward with carbs until the shim job is done. Have the shims to finish the job now from an order, but the 2nd exhaust port had both studs pinged and that was my lynch pin on going forward with the bike as a whole.
I pulled the engine today and got all the studs out. Miracle. My questions are where is a good place to get replacement studs in your opinion and do you think it would be a good idea to tap it out to a larger stud? Say go from a 6mm to an 8mm, for example, while the engine is out? Also, the bike calls for 2.15x18 and 2.50x18 for tires. Stamped on the rim. Do you know a good modern size that is equivalent? The tires are in good condition with no dry rot, but tires are the last place I want to take a gamble. All input is appreciated.

Thanks

PS-It's going to need some external stuff for inspection, but just scored a major coup on eBay for most of that.

 

Instaed of drilling tapping for larger stud, you could drill and tap it for a heli coil, should solve the problem. The tire you have are pretty skinny. Isn't there a raised number set to say the size on the tire? Like for example 110/80 18

 

The 2.15 and 2.50 were the raised numbers.

 

If the holes the studs came out of are still fine, just fit new studs and be done with it.

The studs are the same PN as the ones used in your 550, so Len will have them.

Those numbers cast into the rims are the RIM sizes. Look on the TIRES themselves for the tire sizes.

Your stock rear was a 110/90-18; you can safely go to a 120/90-18 without encountering any fit/rubbing issues. A 4.00-18 will fit also, I'm running one on the rear of my '83 550R. (The FJ600 and 550R had the same rears.)

Your stock front was a 90/90-18; you should be able to go to a 100/90-18 with no issues on the front. A "110" might cause fender clearance issues; I can't be sure (the 550R has a 19" front.)

 

Right now it has a 110 and 130. I have found specs that call for 100 and 120 as well as specs that call for 120/90 18 and 140/90 18.

 

The fiche/factory specs say the '85 FJ600 had a 110/90 as original equipment on the rear, and a 90/90 as OE on the front.

For the rear, I didn't think a 130 or 140 would fit "gracefully." (They won't on the 550R.) If the 130 that's on there isn't having any clearance issues, then you could certainly go with a 130 again.

As for the front, you can generally go "up" one size (to a 100/90) but any wider and you may have fender clearance issues. That being said, if it has a 110 on it now and isn't rubbing, you may be ok; depending on what brand of tire you choose. If it were me, I'd play it safe and go with a 100/90 up front.