morini club track day

[Steve Lake]

Following herculean efforts with gaffer tape, tywraps, hotmelt glue and all the other highly technical tools at our disposal, and burning of midnight and sometimes 3am oil, by me and #1 son we now have 3 (almost) serviceable SRX based track bikes for Thursday....look forward to seeing some thumpeteers there maybe.
Depending on how the ex Andy Duncan bike goes (and its been on the dyno showing 60+ bhp at the back wheel....so boy Duncan got something right  ) we may race it in the supermono series next year.

pip pip

[themoudie]

Bravo!

Sorry I won't be able to attend, was down last week, but earning a pension requires some sort of abstinence! 

All the best, the weather appears to be set fair and there maybe some Duke singles appearing from a well known BHR sponsor, afore going to Pembrey.

Safe scratching, with no nasty bites.

Toodle pip, Bill.

[andy230]

Hurrah!   

Well done steve, glad to hear you will (probably) make it to Cadwell.  Should be a good day.  Any morini's going (I mean, any of "the boy's" morinis, obviously there WILL be morini's there...!).  Did you sort out the fuelling below 3k?  How many hours on the dyno   

Depending on how the ex Andy Duncan bike goes (and its been on the dyno showing 60+ bhp at the back wheel....so boy Duncan got something right  ) we may race it in the supermono series next year.

That would be effing brilliant mate.  I'd love to see that, the achievement of something I wholeheartedly failed to do!!   

A few practice laps doesn't count!!  Which is all those tyres have done, so make sure you use em!!

Post some piccies if you can,  good luck thursday, keep safe,

a

[Steve Lake]

A great day at the races 

no spills lots of thrills, some wonderful bikes on track, including more velo's than you culd shake a stick at.

our 2 'original' track bikes performed above expectations....

Our ex-andy420 bike still has a problem with a misfire/ignition/fuelling problem unless it's in 4th or 5th and wound right open

tried different advances through the rev range, and changing needle positions to no avail, so it's back to the dyno (unfortunately the spare needles and jets orderd form allen performance failed to arrive...so unable to make any further tests, but the performance on track confirmed the dyno results, once 'on song' that is a stonking engine, clearly outperforming similar machines in the same class by a country mile.

anyway....a brilliant day out, and a big thanks to the Morini Riders Club for organising it (the 28th event....something of a record I believe)

[andy230]

Hi Steve,

Glad to hear all was (reasonably!) well.

Our ex-andy420 bike still has a problem with a misfire/ignition/fuelling problem unless it's in 4th or 5th and wound right open

tried different advances through the rev range,

I also tried this, but with the previous ignition system.  That was the reason I wanted that previous (Silent Hektik) ignition system, as I only had to move the pickup thru a curve.  Ignitech requires electronic jiggery-pokery to advance it, right?  I didn't fancy that!

and changing needle positions

I also had a play with this on that day when we were at snetterton steve...  It only made it worse, going either way, so I put it back to where I could to get it to run.

...misfire/ignition/fuelling problem unless it's in 4th or 5th and wound right open
...once 'on song' that is a stonking engine, clearly outperforming similar machines in the same class by a country mile.

Well, that makes me feel a little better!!

Various people suggested various problems to me:

Needles  (dont think so)
Mains (ditto)
Timing (with 2 different set ups, and the same results, changing adv/ ret, I think we've now eliminated that)
Flat-top piston isn't making enough compression (I SERIOUSLY doubt that!!)
Big cam is too much for the flat-top piston (possible, but can only know by buying and changing the cam)

During the course of the project, I cam to realise that there is a big difference between assembling a motor to spec, and building a motor off-spec, and getting something usable.  Keep plugging away steve, and keep us posted,

cheers mate

a

ps.  Are they CR37s??  Maybe going to CR33s would give better low down running?

[Steve Lake]

Hi Andy.....yes, after considerable debate, nay...argument, it transpires that they are in fact CR37's
and yes, going down to 33's is good thinking.....or i could try my single 40mm dellorto...just to prove a point.
i tried changing the advance settings at different rev points...didn't seem to make a lot of difference....
my needles and jets (as advised by Allen Performance) turned up today.....(promised to be with me for wednesday....bless 'em)
so I might try them first.....
there are 3 things that niggle away at the back of my (remaining) brain,
1. ticks over perfectly
2. great at 4k revs plus when opened up
3. plug as black as a witches t*t after a few mins of throttle blipping
4. dyno run showed richness off the scale up to 3k+ revs, then comes within a nats of a perfect mixture up to 8.5k (which is where i set the rev limit on the ignitech cdi.

ok...4 things then


as yet, i can't seem to rationalise, or assimilate this info into a way forward.
onwards and upwards...

[themoudie]

Aye Steve,

My pennys worth, for what its worth!

Seems overcarbed and can't  atomise the fuel sufficiently until the volume of air and venturi effect speeds up. I think your idea of the 40mm or even a 38mm single carb, or the 33mm pair, Andy suggests would be a better way to go.

Duke 350/450 quite happy on road/circuits with 32mm Amal, 120 main, 3.5 slide, can't remember pilot at present. Going up to 34mm for circuits. On the Island where you are hanging on the throttle 'wide', 38mm for 350 is plenty and 40mm for 450. No idea about jetting, but could ask.

Other thought is to try a pair of carbs off an early BMW F650, they look like they might fit with minimal 'flexing' and maybe cheap to acquire. Again no idea about jetting.

Keep us posted!

Toodle pip, Bill.

[Steve Lake]

Hi Bill,
Yes, the bmw carbs (for the rotax engine) are the way to go, a recognised upgrade path for srx motors.
I'm sure you're right, about too large a hole....now i think about it, this engine was running at 690cc until it blew the barrel off, it is now running at 640....,

so could well be too well served for air.......
come to think of it, i'm running a pair of dellorto 33's on my road srx.......there's a thought......
right Bill, you've got me on the right track.....cheers

[Steve H]

4. dyno run showed richness off the scale up to 3k+ revs, then comes within a nats of a perfect mixture up to 8.5k (which is where i set the rev limit on the ignitech cdi.

Steve, I occcasionally buy "Practical Performance Car" which has in the past had some interesting articles on injection systems. One area where fuel injection is supposed to help is with camshafts that have a lot of overlap. At low revs the inlet charge is at very low speed and doesnt have any momentum, as such when the piston comes up on compression and the inlet is still open the charge gets pushed out through the carb, it then gets drawn back in on the next cycle, and since it is being drawn through the carb it picks up more fuel, making for a very rich mixture. I've not seen or experienced this but apparently one way to spot this on open carbs is a standoff wave of fuel vapour on the inlet side of the carb.

The other thing to think about is the fuel curve. The air jet is meant to lean off the air:fuel ratio at higher revs, fitting a larger air jet would weaken the low rev mixture, you would obvioulsy then need to run bigger mains to compensate for the bigger air jets weakening the top-end

[Steve Lake]

Great stuff Steve, thanks.....
I have fitted my trusty 40mm dellorto on homemade manifold, jetted for my roadgoing srx6 (which it ran on for several years)
and lo and behold....works wonderfully, no stuttering or mis-fire anywhere...which almost certainly proves what you and Bill are telling me.

the single dellorto is probably about 2/3 the the total area of the 2 CR37's, on a somewhat restrictive manifold, so i'd guess that there is a good air speed (and hence, depression) to atomise the fuel, it is also running a long inlet trumpet which should help.

so its off to the dyno tomorrow to see how much power i've lost, and then make a decision on whether to go for a pair of 33's.

thanks for the info

[andy230]

Well, that sounds promising then Steve!

works wonderfully, no stuttering or mis-fire anywhere...which almost certainly proves what you and Bill are telling me.
thanks for the info

Good old ThumperClub   

so its off to the dyno tomorrow to see how much power i've lost, and then make a decision on whether to go for a pair of 33's.

Good luck, let us know how you get on!  I wonder if you could find someone needing a pair of 37's, to swap for 33s....?

andy

[Steve Lake]

My thoughts exactly Andy!

Andy....what was the history of the front braking setup?
lovely radial caliper...equally nice machined mounting adaptor block

but pads only working on 2/3 of disc....
initially i thought it must be set up for a 320 disc and its a 300 disc fitted
but it apperas to be a 320 disc already?

[themoudie]

so its off to the dyno tomorrow to see how much power i've lost, and then make a decision on whether to go for a pair of 33's.

thanks for the info

Read your email messages! 

Bill.

[andy230]

Hi Steve

Originally brakes (like forks) were KR1S.  With 2x yamaha 300mm disks.  But I wanted a single 320mm disk.

Brake caliper mount was made by DBR (MArk, a mate of Ash), but they appear to have quietly disappeared....!  Very good engineer tho.

See here -->

http://team-thumper.blogspot.com/2008/10/bling-bling.html

The caliper came from Ash, as did the Honda RS250 (track) m/cylinder.

I noticed that the pads were on the extreme outside edge, but is there actually any friction material unused??  I know not all the disk is getting contact, but thought it was ok re. the pad position...

KR1S calipers would go on to the fork legs, but probably not mate well with the disk now...?

CHeers for now

a

[andy230]

And, from Bill Jurgenson:

I said:
> We now know the carbs are not CR33s, but CR37s!  Oops!  I never measured
> them, and was told they were 33mm and I did not check.  So this may explain
> its inability to fuel properly at low revs.  Do you think?  Cannot get air
> flow fast enough??

no wonder it won't run under 3000! Not enough vacuum at the needle jet
which makes a far too large jet (not main jet) and high hug leddle
necessary. Probably also too low a cutout of the slider and too large
an idel jet. All necessary to get subsitute for the lack of vacuum.

Just thought i'd add that to the pot!

a