Running in speeds

[rustyrim]

Hi,
Great weather for a spin on the fizz.
I’m running in at the moment- about 200 miles now. How many miles are you guys doing before you take the mighty fizz up to about 40 ish?
I’ve been plodding around 30mph for the last 100 miles, yet it’s getting a bit lumpy. I’m not talking about ringing its neck quiet yet; I reckon with modern oils, engine feeling looser, that it’s time to up the revs a bit.

[allspeed]

I been doing the same since saturday , 62 miles on so far with no nip up or overheating. Its important to use full throttle from low speeds and takes the revs up high in first and second or the bore will glaze over. I aint been over 43 in top and dont hold it full out in top for to long. As for how long it depends on how tight the piston clearance was to begin with . Did you measure it ? what kit is it ? Mine had a very healthy 2.5 thou clearance so theres little chance of a nip but its still good to settle it in before wringing its neck.
Mine feels free enough to give it some but im refraining, and its staying pretty cool. I plan on getting out every night this week to get it done.

One things for sure its going to need a 15 front on mine, its running a lot of revs in top and pulls 4th far to easy for my liking

[rustyrim]

Hi ya,
Thanks for the advice. That’s what I have been doing more of... opening up in 1st and 2nd and not letting it bog-down on hills.
No, didn’t check piston clearance . Should have. Do you place the ring in the bore and then measure the gap? Is so, I will do it next time.
I’m running a FS1 skimmed head and a FS1 (1.50 over) mild tuned barrel. I didn’t want to go too far with the tune because I still wanted a good spread of mid-range power. Otherwise I'll be ringing its neck all the time. So far I am pleased, good range of power in 3rd, especially when it hits hills. It pulls well without screaming it nuts off.
I think it’s time to take it up a bit more in top.
Cheers.

[allspeed]

Whenever you get a rebore on a fizz or a new kit its a good idea to insert the rings into the top of the bore,then push them down 10mm or so with the piston skirt so they are square and measure the open end gap. Anything from 4 thou to 8 is fine for new rings. Its normally ok when you check it anyway, more important is to place the piston 1/3 up into the bore and see what size feeler gauge you can get down past the skirt to the bore (From below). Some of the cheap kits only have a thou or just over, this is very tight and will take some running in and will likely nip several times. Ignore Yamaha's spec , if its two thou clearance thats good and running in should be pain free.

I wouldnt worry now, fit an 8 plug and just get the miles on, it sounds like you know exactly what your doing.

First one to 55 wins a Teapot

[rustyrim]

Thanks for the sound information, worth knowing.
If you fit that 15 front- you'll win the teapot.

[allspeed]

Got 125 miles on it now, still running sweet with no hint of tightness. Did a 25 miles in one hit stint today without a pause, worked it a little harder though still staying under 45 and the bugger nipped twice on me at the end of the 25 miles. Took me by surprise. I let it fully cool down( but it wasnt silly hot).On the home trip it was fine, i just held it in top at 43 for too long today on the fresh top end. Thats my lesson learnt Im getting 200 hundred miles on it before i give it any more beans.

Also took the top off and no damage was done that would'nt clean up and im good to go again tommorow.

[rustyrim]

I recon your right- about 200 miles before you give it some beans. A minor nip isn’t going to cause any harm.
Yesterday, I did a further 15 miles, and then took it up to about 40ish in 4th. However, it was revving too high for my liking. So back to the garage for a pitstop. ‘Now where’s that 15 tooth front sprocket?’ After a quick search it was found. It fitted ok, especially as the new chain had loosened.
I decided after another few miles that it was time to open up... It bloody flies; I was pulling 50 up a slight incline- adrenaline flowing through my veins, not believing what the Speedo was reading. After my heart stopped racing, I decided not to thrash it anymore. Instead, I immersed myself in the summer’s evening, pottering home with a smug smile of satisfaction.
I have sacrificed a slight dip in power pickup between 3rd and 4th - so I have to give it a bit more revs in 3rd to make it pull in 4th. Yet I remember that was the case when I was a first time fizzy freak.
I’m certainly happy with the tuning work done by Mick Abbey; he has given the fizz a good spread of mid-range power without burning a hole in my pocket.
I might do a few more miles until I try to reach a mighty 55. So until then, the teapot is still up for grabs.

[allspeed]

Sounds ace, i havent been around a fizzy tuned by mick yet but sounds great. Mines screaming for a 15 which in one ways a shame as it pulls so nice like it is but im running out of revs so its gonna get one.
Also fitted a 160 main jet after my nippage Performance is no different but will help to keep the motor cool. What speed are you having to rev to in 3rd before it pulls 4th cleanly on the 15 ?

[rustyrim]

Over 40 in 3rd if I want a good pickup into 4th.

[allspeed]

Mmmmm Dont think mine will do 40 in 3rd, i can see the Teapot slipping out of my grasp..

Another 15 miles on this salvo, a problem in the fuel supply has been highlighted, a problem im not sure how to deal with yet. Pherhaps two float chamber gaskets will be a start, before i resort to bigger bore petrol hose. Its gobbling it quicker than i can get it in there. When i back off at around 45 in 4th, pulling the clutch in and blipping the engine till me speed drops is accompanied by the engine revs soaring when i back off . Its soaring with sudden weak mixture, it did this once before when the tap got partially blocked so i reconise the symtoms. It was at this point yesterday it nipped so need to sort it.

The chances of the tap being obstructed again are slim but i guess i need to check there first before working my way down.

140 miles on so far And its mighty in the midrange