Rode the Sprint today

[DougErickson]

I put 5 or 6 miles on it and am pretty pleased, starts right up, pulls good,clutch feels great ( I was really worried about that), shifts real nice, handles light and neutral, front brake is pretty strong, rear is OK. Only significant glitch is it has a hanging idle and I suspect my adapter ring for the Mikuni is not sealing perfectly and allowing an air leak but the only aerosol I have at the house at the moment is WD40 and I didn't want the mess of testing with that. I may try making a new adapter ring that will bring the carb closer to horizontal and epoxy it on. All that good stuff and it is easy on the eyes too! Doug

[John H]

Good going Doug. Sounds like a fun rider. If you don't have an air leak or a float level surge, might think about tired springs in the ignition advance unit.
Ride on over when you have time.

[DougErickson]

Good input John, thanks, I'll get back to it soon. I am wondering about oil for it too, since it is a dry clutch would it be good to go synthetic like Mobil1 which would be convenient since we use that in the Mustang or should I go Castrol GO 20w50 4T oil like I run in the Bonneville? Any thoughts?

[John H]

Doug, Castrol is a good choice. I like to use the Valvoline VR1 20-50 synthetic with ZDDP (zinc).

[Dragonknee]

Looking forward to seeing the bike together and running for sure.

[DougErickson]

I made some changes to the Sprint and took it out this afternoon for about 40 more miles. The biggest change was the jetting in the new 30mm mikuni. It came with a 40 pilot and a 250 main. It seemed the plug was a little dark and I had to back out the air screw 3 turns to optimize it, it didn't like choke cold starting, plus the hanging idle problem so I decided to lean it out and see if that helps. I dug through the GPP (giant pile o'parts) and found a 22.5 pilot and a 190 main, wow! better in every way. That little bike is really growing on me and I am pretty surprised at the decent power it is making. I took it up to 70 on 101 and there was more to be had. I think it may even outrun XL250's up Morse creek hill (Jay)! It has been fun and I'm not done yet!

[John H]

Doug,
These Sprints were the thing to have in short track racing along with Ducati until the two strokes came along. When that happened, you could buy them cheap. How time changes.
This 350 Sprint has held the APS gas record for 12 years. The Jawa that I got from Anders J. still has the fuel record.

Bonneville records.png (13.67 KiB) Viewed 12226 times

[ClineDesign]

That little bike is really growing on me and I am pretty surprised at the decent power it is making. I took it up to 70 on 101 and there was more to be had. I think it may even outrun XL250's up Morse creek hill (Jay)! It has been fun and I'm not done yet!

Hah, my XL250 tops out at about 60 on a straight, flat stretch. Maybe if I lose a few pounds it'll do 65!

[John H]

Doug,
Here's your chance for a few more Sprints.
https://seattle.craigslist.org/est/mcy/ ... 05364.html

[Lotus54]

I have a few of those back in the 70s. Fun bikes.

I (foolishly) bought a 72 Benelli 250 SuperSport- similar engine layout, although very oversquare and I recall the Sprint was undersquare.
We will have to go for a ride with the old beasts when I get it and get it streetable.

Mark