The second project...'Tiggy'

[andy230]

bluddy 'ell!... #1 son reckons its a widow maker, lifts the front in 1st and 2nd....

Great stuff, very pleased to hear it!  Remember the brakes and suspension haven't had the same attention as the motor mate!!  May need a bit of dialling in, so go careful round the gooseneck!!

The rear shock was rebuilt, but only roughly set up statically, and unless you've changed them, the forks will be a bit "suck it and see".

Yes, I thought the silencers were too loud, and re-packed them to no avail!!  I tried dB killers in there, but only made it slightly quieter and no longer ridable!

100 quid on the dyno sounds like an absolute bargain.  Is it the "Ignitech" ignition system you are using??

Keep us posted, and enjoy.  If you can find a class, you'll be racing it next.....

a

[Steve Lake]

Yes Andy, it is the ignitech unit... which reminds me, i must go see the dyno fella at X-bikes, he (hopefully) has the current ignition profile on his pc, I know i can download it from the unit, but right now i'm going to leave it 'as is' on the 'if it aint broke, don't fix it' principle....but it would be handy to have the working profile in case the unit goes back to default or summat.

incidently, last night, whilst tidying up the wiring round the ignition/coil/tacho area... I found a handily crushed red wire which had, at some stage been shorting out... almost certainly the cause of the blown battery... so that was a bonus

with regard to the Db rating.... i noticed, when we ran it up the other night (with #1 son doing a passable impression of joey dunlop testing the bike up and down the local back lane) that it didn't seem as noisy as it was on the last outing at cadwell...might be my imagination or might be that, with the carbs and timing set up it's a bit calmer... we'll no doubt find out tomorrow 

MRC testing day report and pics to follow...   weather don't look too promising, but cadwell does have it's own microclimate, so here's hoping

[Steve Lake]

What a bu55er!...  tiggy went really well on the first session... i was starting to get used to the stunning handling, and the enourmous grunt.... it's an eye opener to ride a purpose built racing chassis with good suspension and tyres.... nothing could get near it on the straight, and it was so easy to carry corner speed...flip it into corners so easily...wonderful...
#1 son took it out on the 2nd session, and once he got passed me i couldn't get near him... and watching him in front the bike looked so good.... i did manage to show him my front wheel on a do or die outbreaking attempt... then it was the end of the session... i followed him round on the 'in' lap... he suddenly slowed, and as i pulled alongside i heard this sickening rattle.......

he was dumped out of the broom waggon 10 minutes later.... with the bike on the track stand and 2nd gear engaged, i tried to turn the engine over, 'clunk' and jammed solid... so... as far as i can tell it's probably a dropped valve, whether the collets came adrift and the whole valve dropped, or the stem broke, i won't know until we break it down...

I'll need to chat to Andy, as he has an intimate knowledge of the head, and what went into building it.

Anyway, back to the old standby bikes for the rest of the track day... and a good time was had until rain stopped play mid afternoon.

also, i noticed another crack in the frame, weeping oil, and the one i repaired is also a bit porus, so i'm thinking i'm going to get the whole chassis back to Martin Sweet at Tigcraft, to give it a once over, and replace the lugs so's i can fit my stonking SRX6 tuned engine that is running in my unfaired track bike at present, then at least we can get out a few more times this year... watch this space

[Steve Lake]

oops, for Martin Sweet read Dave Pearce, Martin of course is the man behind slipstream racing

[andy230]

Ach Steve!      Terrible news!!   

On the (very minor) plus side, at least the handling is not a million miles out for another motor to go in...   

Drop me a line, you still have my address?

Motor will have to come out to get the head off to get a look....

Ah feck...

a

[Steve Lake]

Andy.... Any info on the head would be handy... type of valves, where they came from.
are they special caps or standard srx.... likewise collets etc etc

[andy230]

Hi Steve

All info is in the little black book of the build.

I can't remember offhand what the head is.... XT?? Tenere??

The valves are standard, just cleaned up on the back for a slightly better flow.  Probably academic...

http://team-thumper.blogspot.com/2008/02/devil-is-in-detail.html

and

http://team-thumper.blogspot.com/2008/02/return-of-anorak.html

However, I do remember that there are 2 different sizes of valves, which are 1mm different.  I seem to remember measuring the ones that came out, and they were (strangely) the smaller size- not as expected in a race motor.

However, bigger ones wouldn't have fitted the head, so I went with (new, Yam) smaller ones (didn't fancy the cheaper pattern ones I also sourced from Kedo).  I think these Yam ones were marked 34K  (??Tenere??)

As I say, all notes (inc. Yamaha data, and some from Steve's site) are in there.

Springs I think came from RD.

Is this any use?

http://team-thumper.blogspot.com/2008/05/terrible-headaches.html

nb. That last line!!

Collets are standard Yam, but very slightly dressed for clearance of the seal....    Do you think this has been the issue?

Did it drop a valve??  Lost collets??

Emailed you but happy to chat here...

Cheers

a

[themoudie]

Oh! What memories!

Coil bound springs? 

Tiss got I thinking, after I found valve stem seals 'minced' and yo-yoing with the valve, rather than attached to the valve guide. The inner springs had picked up on the outer cover of the seals and appeared to have pulled them off.

Smaller diameter valves would potentially give higher gas flow rates and 'mask' less. Also less mass to move at higher rpm.

Please keep I posted or as Cc.

Ta everso, Bill.

[andy230]

Ummm, yes,... interesting idea Bill.  Yours has a big can in it, eh?  I think the guides had already been modd'ed for a big un...  Seals (new, Yam) were on as far as they'd go...

Springs shouldn't have been coil bound, due to set up as per spec sheet with the springs... 

Agreed about the smaller diam valves Bill, or maybe it was just that the head was already good, so the previous builder went with what he had.

Interesting, if rather grisly and unpleasant post-mortem.  Any update from the pathologist?

a

[Steve Lake]

no, not yet.... will be stripping chassis out this weekend prior to delivering to Dave.... then i'll be looking at the mill, probably monday or tuesday.... just to keep everyone guessing :-)

[themoudie]

Aye Steve,

Your going to miss BHR at Cadwell this weekend, 2 day event. Unfortunately, I am in the same boat, but may be able to arrange the end of September one.

As for reading the entrails, I wish you well and hope that the seizure has not grenaded everything inside. Big ends don't like 'stopping' suddenly!

My regards and hope the sun shines. 

Bill.

[Steve Lake]

yes Bill, cadwell would have been good this weekend.... great waether in prospect for sunday.
Still... i'll have to make do with BSB at snetterton next weekend (bet it'll be wet)

have a good weekend everyone

[Steve Lake]

Right... nice sunny day... swmbo off out to visit some gardens.... time for me to have a look at the engine.
fairly easy job to drop it out of the tigcraft chassis.....
once out, the rocker cover comes off... and all looks good in there
next the head comes off and everything looks fine there too
now the clutch cover comes off, and.... oh bugger.... loads of teeth all over the place, the the sprocket on the crankshaft that drives the balance shaft 80% stripped and the sprocket on the end of the balance shaft is in a similar state... heaven knows what could have caused this, possibly a foriegn body.. or a broken tooth... i guess i'll maybe know more as i break the motor down further..
tried to post some pics, but says upload folder is full.... stick some up asap

[Steve H]

tried to post some pics, but says upload folder is full.... stick some up asap

Now fixed

[andy230]

Hmmm, that would explain it then!

Am not sure if its good or bad news tho... Good that the new piston, valves, springs etc are not scrap.  That would pain me (and you)!!

Tho I suppose the bottom end will be dearer and harder to fix.

I have heard in the past that the balancer shaft teeth are not the strongest, and these ones have had a lot of hard use for a number of years...  I suppose we are asking quite a lot, from a motor that normally puts out under 50 bhp... Nearly a 50% increase.  Tho that was the rationaly for using the 660 bottom end.... (tho maybe the internal parts are the same and just the cases are stronger)

Keep us posted mate, I may have some bits under my bench for the Skorpion if you need.  Not sure whats there, but can have a look if you post some piccies?

Cheers

a