Made some great progress being stuck at home, engine in, all cabled up, took a bit of time to setup the clutch, very sensitive on adjustments! Fuelled and running, everything works fine, test run tomorrow
So, test ride day. Initially clutch was not disengaging, adjusted up with a slight drag, started and selected gears ok but high bite point, as soon as on the road it slipped so just sticking plates as the engine has been standing for a while, back in the garage and slackened off, 2nd run and the engine started to clear itself, still a small slip, slackened off again and third run.
The engine clearly wants to just go, it was tough trying to tickle the revs, clutch now fine once warm and got some oil around the plates, what surprised me is just how sedate it can be ridden, even with this level of tune and a 34mm carb you can change gear at 2000 revs and it pulls, I'm guessing the extra torque from the bigger 154cc and 54mm crank. Only ran a mile and back in the garage to check everything, clearly the pipe is meant for power and revs, despite the low end grunt when i raised the revs it wanted to just let go, the pipe is a falc based system so will want to rev from about 5-6k to come on power but you can feel that.
A couple of nipped up bolts, plug check and 1/4 turn in on the mixture screw, rechecked the timing and sitting at 25 degrees at around 1500revs, so now ready to run in which will be a pleasure as it can tootle along for a few miles before we can open it up which i can't wait for, patience required!
So disaster, went for another running in ride, came to a junction, changed down, clunk, no clutch Stripped down the side casing, head scratch, so engine back out again, everything looked ok, clutch and lever fine.
Stripped the actuator and here’s the problem, The plunger is the ‘race’ version from SIP so expected this to be much harder, clearly the heavy Fabbri clutch was too much for it.
Sent SIP a mail and pics and they’re putting one in today’s courier, this only lasted 5 miles so maybe need to review the clutch/spring combination Absolutely pissed as it was feeling fun, now engine on the bench for a third time,
Quick update on the clutch woes, after carefully stripping and measuring the clear issue is actually with the clutch, in my build the Fabbri clutch does not have sufficient separation room, the design of the pressure plate means it actually sits on the circlip so in effect has little over 1mm travel, hence the pushrod was stressing on the clutch, hence the failure. Happy to share all the pics and measurements if anyone else has this clutch, you can get around it with either turning down the pressure plate (which I have done) or swapping for an alternative plate to give optimum clearance.
I just lost confidence with this unit and the design so I opted to order a Crimaz CM4 from Christian, it arrived today and looks great, it fits perfectly and is quite unique design, the plates are carbon but the steels have a small notch that sits in the basket, I had to assemble in situ as the gearing basket is billet but with the right compressor was fully fitted in minutes. The included bearing pressure plate is great and has total clearance so plenty of room. The action is stiff but reasonable and not as stiff as the Fabbri.
Whilst waiting for a few new gaskets to put the engine back in I tackled the SIP speedo, I think I’ve scratched ever finger trying to feed all the wiring in, welding wire comes in handy! I managed to fit the control box in the headset using double sided Velcro! I opted for the electrical speedo drive, I have one on the Lambretta and seem very accurate if you set the computer correctly, measure the rolling circumference and don’t rely on the base settings is a good pointer.
Also fitted the glovebox, I did use the Scitsu Rev counter as it was planned for a Monza engine but is incredibly accurate, I’m running this of a 12v power pack in the glovebox.
If a clutch could ever be a thing of beauty, then that Crimaz unit is - v nice....not surprised it fits well
Hi Nick, after many years of the small frame clutch discussions, we are now lucky to have some great options and Crimaz has bought some great engineering to the market. There is still a mixed bag of results in real terms and usage but this is a well thought out solution at a reasonable price, I was cautious of returning to a centre spring operation but on the bench and fitted it seems to work very efficiently, that said, I’ve purchased high cost multi spring units that don’t work!
I fitted the Fabbri clutch to my Pollini Evo motor and had to open up the pressure plate bearing holder and file the corners of the nut down to get it to fit and release correctly. If you measure everything its designed to only have 2mm of separation , I thought this wouldn't be enough but it seems to work OK ATM though I haven't run it for that many miles
Look forward to hearing what it’s like on the road....
Initial thoughts, the lever is actually very light, Crimaz recommend a lever with 25mm fulcrum which a dogleg has, plus the XL2 geared cover etc... initially dragged slightly but the carbon plates I find do need a bit of a bedding in, I’m running with an 80-90 oil as recommended. as the engine is new I am only revving to 5k so not enough to give feedback on full load capacity/slipping but feels very nice. The addition of the SIP quick shift roller is a revelation, wish I had seen these on the other smallies, literally a couple of mm to change gear, best £20 of the build. Will report back on the clutch when we can give it some abuse!
A quick update after a few days running in, the engine drives perfectly, goes through the gears clean and picks up from very low revs, you can change gears at 2-3K and it just purrs along. Kept around 4-5000rpm, although this morning I gave it a quick blast up to 8K in second gear, jeez it’s a handful and will be incredible after a few more miles, aiming for 50 then build up to full power. The Crimaz clutch performs well, it is still a bit ‘snatchy’ when pulling off, bite point is either in/out!
Had to tighten a few things today as expected, plus retard the timing slightly, back to 24 degrees at 1500 revs.
A few issues: The front tyre rubs on the shock absorber, it’s a tiny amount but is enough to rub and drag, it only needs about 1mm clearance so ordered a few shims as really don’t want to use 3.00 tyres. Then the big problem, the brakes! Even with the Malossi shoes there not great, especially when it’s running full power, so it will need a disc at some point. The carb does spit a lot, so the inner frame and loom are covered in oil/petrol, I have a ram air filter so will try but I usually find they hate having a filter, my Lambretta Super Monza wont run with a filter!
What are people running, either the simple converted PK forks or has anyone used the a Crimaz conversion for the std setup?
Keep an eye on the plates with the clutch if it’s biting hard. Had that on my M1 with one clutch and after a few hundred miles the tabs had grown ears that stopped the clutch engaging....was also related to a clutch basket that had no cush effect...
Hi, I've been following your build as I'm thinking of using the same kit with a 54 crank on my next engine build. I have a few questions that will be very helpful if you can answer please Do you know what exhaust and transfer timings you ended up with once you adjusted the squish to .78? Did SRT change any port heights or shapes in the barrel or did they just match up the transfers at the base of the barrel/casing? Were any adjustments made to the head volume or is it as it came standard with the kit? Would be very interested in seeing the Dyno graph when you have it after all your hard work on this motor.
I'm running a PK fork, Grimeca classic semi hydraulic, SIP calliper with Typhoon master cylinder under front mudguard.
Upgrades turned up today to improve the braking, clearly need a good disc setup, I opted for the Crimaz kit to fit the original fork, I had ordered the standard kit but surprisingly the new billet one turned up at the old price (not complaining), the setup looks very well engineered as expected. The bearings I ordered online from a bearing specialist, worked out under £5 for 2 sealed SKF genuine ones, amazing difference than paying the markup. Just awaiting the new front axle from LTH as they were the only ones with a genuine item in stock, also the Crimaz billet unit does not use the threaded ring inside the housing, both bearings are circlip fixings. Something to do this weekend!
Fitted the disc brake this week, usual Crimaz quality, it’s great to buy parts that actually fit with grinding or drilling! The handlebar cylinder is also from him and is a work of art, I used AN3 braided hoses and fittings, so much easier to buy the bits and make them up, the fittings are around £5-6 and the hose can be got for around £7 a metre, the dealers are asking up to £80 for a hose ( I used to use them all round on my rally cars). Very simple to fit, it’s not something outside the scope of any mechanically minded person. Also fitted the original runners and found a genuine, new Piaggio seat in Germany, so now a bit of a street sleeper. The travel on the master cylinder is quite long, I have a pressure bleeder but still feels like there’s air in, it’s not but just a lot of travel. The billet brake kit is very well engineered, the custom hub is a straight swap, the speedo cable has been reconfigured slightly so the rubber bush fits on the outer with a plate similar to a PX.
It’s a tight fit feeding the braided hose and speedo cable in the forks, patience is required! First road test takes a little getting used too, mainly due the the travel on the lever, then it bites hard! Great to have really modern brakes but you have to have a light touch, especially in the damp as it will lock up. Crimaz recommend fitting with the anti dive which I have, overall a great safety upgrade that looks very good.