Seeley (replica) Framed Project Road Racer

[Suzukidave]

I know how to post pictures but a sticky with the instructions would be handy for first timers

[Zunspec4]

Hi all,

Today I spent a few hours at the workshop of Pete Odell assessing and then rebuilding the failed crank. Spinning the crank between centres, all dial gauged up, did not show any signs of twisting. However the LH rod had been assembled too tightly and this is the prime suspect for the big end failure. However the rod has a strange "S" bend to it, as if it had been bent and someone had tried to straighten it, bit of a puzzle this as Pete has never seen this as a result of running. The crank may have been dropped, but who knows. The crank has been rebuilt with new rods, crank pin, big ends, shims etc. and is good to go back in the engine . Examination of the LH barrel & piston shows they don't need any attention and they will be re-used.
Some photos of the carnage, undamaged b-end is also shown for comparison

Crank damage and rebuild by zunspec, on Flickr

[Suspensionking]

Interesting and very strange. Do you run premix or are you also running the oil pump?
to bend the rod like that you would expect to see some damage to the piston top or the head if they touched, unless like you suggest the rod got dropped.
I just had my crank rebuilt because I though it might be the cause of the excessive vibration, It all seemed ok but we rebuilt it anyway, but it did not help to reduce the vibration.

On a side note I have changed to running ETC classic race fuel 110 Octane and its amazing how much cleaner the engine runs.

Cheers

Eamonn

[Zunspec4]

Hello Eamonn,

Yes, I use pre-mix @ 25:1 Castrol A747. The piston and bore were in good condition (after about 170 race laps anyway ), although the bend in the rod may have happened if the piston hit the head as you suggest. I will have a closer look with that in mind although the minor marks on the piston crown I put down to debris from the big end breaking up.

I was running on a blend of 50:50 100LL AvGas and premium unleaded (97 RON) as race fuel of 110 Octane is outside the 105 RON limit for the class.

Here's a pic of the rod after we first removed it.


Cheers Geoff

[Suspensionking]

well That looks pretty bad. 170 race laps depending on the track length but say average 2.5 miles per lap thats about 425 miles not a lot really. I would expect a lot more before a crank rebuild as these motors only rev to around 9000rpm. on my engine Thierry removed quite a lot of material from the crank and used nylon packers in the cases. I run 3% so 30:1 with the race fuel and I changed to ELF 909 I have always used 747 but was not convinced it was the best. 909 is much thicker so needs a lot of mixing. I have just one more race in the Suzuki in October and will have the Friday before the race to test at Calafat. Still trying to work on the carbs to get it to pull out of the corners cleaner. Problem is with the Nova CR gearbox the 1st gear is very long and it bogs in 2nd on the tight circuits like Calafat. I have a national race on my 350 TSS Bultaco in Valenica 17th September and finally seem to have got that bike reliable after one and a half years of trying.
I am going to plan a 2 day test in Spain next year March time before the season if you are ever interested in running your bike down there let me know

cheers
Eamonn

[Zunspec4]

Hi Eamonn,

I would fully agree that I should not have had this failure after such a low milage. I have to put it down to bad luck, although I have some reservations on how the crank was rebuilt (not by Pete Odell I hasten to add). This engine was designated the "banker" it was hardly tuned above std. spec and only revved to 8000rpm. The proper "race" engine is still awaited. It has a lightened crank and has a much more adventurous porting and 38mm carbs. Your 350SS Bultaco sounds very interesting, any chance of some photos?. Two days testing in Spain sounds a dream, I'd love to do it if the finances allowed.

Cheers Geoff

[Suspensionking]

Geoff

The Bultaco is actually a replica build by a company in Spain AJR. they made 54 of these and mine is number 52. It quite a lot different to the original but looks the same. It has 6 speed Nova CR gearbox and 6 transfer posts where the original had only 4 as it was a MX motor. However it is light 93 kilo nad with 60 HP it plus like a train. However setting it up has taken a lot of sweat and expensive piston replacements. Seems good now at least last time out. It was built for small Spanish people so was difficult for me to ride at first but we have step by step moved things around and now it feels more comfortable. I built some longer Fox shocks for my last race and that really helped the steering. I just struggle to get used to drum brakes they seem to be on or off.
I will need to email you oils as I am unable to lose them here. It is for sure a interesting bike.

cheers

Eamonn

[Zunspec4]

Hello Eamonn,

I will PM my email address as I would like a peek at that Bultaco. 60bhp and only 93Kg it must be a real flyer.

Cheers Geoff

[Suspensionking]

Geoff I sent some pictures by email I will take some more interesting one`s at Valencia

[johnu]

Zunspec4, I just read the whole thread Awesome project I love it I will have some questions for you soon as I am building (rebuilding) a t500 special that I built.

[Zunspec4]

Hello John,

A project with highs and lows Race wins and engine meltdowns. There is no reason why the T500 engine cannot be fast and reliable though. When I first raced one in 1980/81 I did 17 meetings with not much more than ring/piston changes to maintain optimum sealing. I have just finished making good the engine that seized it's crank at Cadwell and the proper "race" engine will hopefully be available soon.

Good luck with your bike and if I can be of any assistance just ask.

Cheers Geoff

[johnu]

Hello John,

A project with highs and lows Race wins and engine meltdowns. There is no reason why the T500 engine cannot be fast and reliable though. When I first raced one in 1980/81 I did 17 meetings with not much more than ring/piston changes to maintain optimum sealing. I have just finished making good the engine that seized it's crank at Cadwell and the proper "race" engine will hopefully be available soon.

Good luck with your bike and if I can be of any assistance just ask.

Cheers Geoff

Ok thanks Geoff! Always highs and lows in racing, been there and done that That frame is a work of art, I love the raw metal with the brazed joints! As I recall you are still running the oil pump right, not premix? Oh, and are you using Wiseco pistons?
Here is a link to the thread I just started on here yesterday if interested viewtopic.php?f=21&t=12577" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
I posted a short video on there as well.

John

[Zunspec4]

Hello John,

I only ran the oil pump in the engines first incarnation, swapped to pre-mix after that (20 or 25 : 1 , Castrol A747 . 50:50 blend of 100LL AvGas:Premium Unleaded).

I have been running Wiseco or Wossner pistons.

Love the style of your bike

Cheers Geoff

[johnu]

Hey Geoff,

I'm seriously considering going premix as I hate dinking around with that pump and those crazy oil lines. I am going to be running leaded race gas Sunnoco 110 Standard. What did you have to do inside the engine to go premix and do you think that was anything to do with your crank issue?

Thanks,
John.

[Zunspec4]

Hi John,

I posted a few photo's on the "T500 oil injection" thread, which I think you have glanced at, showing what's needed to go pre-mix. Basically you omit the "Plate, Oil guide" and replace it with an equal thickness shim and build up the crank as normal. I don't believe the use of pre-mix vice the pump had anything to do with the crank seizure. Retaining the oil pump and lines has a lot to commend it though. Saying that you do need a sound set of lines and pump, something that the age of original components does not necessarily deliver.

Cheers Geoff