Mikuni RS36 carbs

murphus said:
Any opinions on replacing my originals with new PHF32s? There's a fellow in Italy with whom I've dealt before, $804 for 3 delivered. They are standard cable-operated type so the domes/linkage would have to be swapped over. When I last had my carbs apart, which wasn't too many miles ago, the linkage and such all appeared to be in excellent shape, but ... And of course the ones he has would all be handed the same, with mixture screw on the same side.
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Mixture screw on the same side?

Paul
 
murphus said:
Any opinions on replacing my originals with new PHF32s? There's a fellow in Italy with whom I've dealt before, $804 for 3 delivered. They are standard cable-operated type so the domes/linkage would have to be swapped over. When I last had my carbs apart, which wasn't too many miles ago, the linkage and such all appeared to be in excellent shape, but ... And of course the ones he has would all be handed the same, with mixture screw on the same side.
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Conversion isn't as easy as it first appears. Vacuum bores aren't usually drilled, also the bores to attach the large rear bracket. Depending on casting type, this may not even be possible at all. Some, not all, PHB/F carb castings have the additional material to accomodate the bracket. Drilling these holes needs to be pretty accurate, otherwise the carbs may end up to be impossible to balance.

Having the mixture screws on the same side adds to the pita.

piet
 
If your existing carb bodies aren't too worn in the slide bore, you can re-furbish them. All other wearing parts (slides, needles, jets, etc.) are replaceable. If the throttle shafts in the top domes are worn, you can probably re-bush them (can't say for sure because I've never attempted it). I'm not sure what the prices are like for Dellorto parts these days. it's been a long time since I bought any.
 
There are places that do a Teflon carb slide coating that takes up wear and reduces friction. It's a bit hit-and-miss though. I had it done on a Delordo from a Husky and it worked great. That bike had a horrible jerky engine performance just off idle losing traction on hills, especially in wet weather and that coating made that into a creamy smooth pull. Tried it on a set from my 3C and it blistered and was unfixable, they looked like they had the mumps. At $80 each back then an expensive fail to replace them.
 
I know that the slides themselves show some visible wear/scoring, but I'm unsure how/if that's been transmitted to the actual bore. Slides are available, so ostensibly if the bores are OK new slides should have a marked positive impact. As to slide coatings, I remember having a set of Amals on my last Norton Commando bored and fitted with chromed slides to suit. Some fellow in Texas, as I recall, and I'm thinking he used Mikuni slides. The conversion negated the choke, which was just a secondary slide to impede airflow, and it worked brilliantly.
 

sfcpiet said:
Conversion isn't as easy as it first appears. Vacuum bores aren't usually drilled, also the bores to attach the large rear bracket. Depending on casting type, this may not even be possible at all. Some, not all, PHB/F carb castings have the additional material to accomodate the bracket. Drilling these holes needs to be pretty accurate, otherwise the carbs may end up to be impossible to balance.

Having the mixture screws on the same side adds to the pita.

piet
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Thanks for that info, Piet. I had assumed - always dangerous - it was a simple matter of tranfering the correct parts. Good to know it's not before buying parts and only then discovering what's actually involved.
 
Paul Marx said:
I'd be quite tempted by a set for my 3C. I'm quite convinced that along with the Ignitech, they'll make the machine more mellow. However, I've already thrown a lot of cash at that bike, but who knows....
The Ignitech is amazing. Was out yesterday evening with Corinne on the back. Two up therefore, the bike will pull from 1800 revs until the limiter where ever that's set.

Paul
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Witt DMC and IIS solved the low rpm jerkathon long before ignitech was even a dream, especially on the 120 motors which suffered most of all, from low rpm wacking 5DBTDC to 32DBTDC at less than 2Krpm... glad you like your ignitech Paul, it is all the same a post era product with user variable setup capability, a technical feat not to be underestimated or overlooked, it has its feature superior to previous era, yet it did not lead the way. j.
 
Can anyone tell me which Ignitech system is applicable to a 120 Laverda? Currently running an ancient MotoWitt and wondering if there is any improvement to be found. I went to their site, but there is nothing to indicate which unit is preferred.
 
Alzero said:
Can anyone tell me which Ignitech system is applicable to a 120 Laverda? Currently running an ancient MotoWitt and wondering if there is any improvement to be found. I went to their site, but there is nothing to indicate which unit is preferred.
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The unit you need is a 4-channel version of their TCIP4 (they come in 2 and 4 channel versions). Just tell them what it's for and they'll pre-load it with suitable software.

Also tell them what pickups you're using. Their units use different internal hardware (or firmware?) for Hall pickups than they do for VR (magnetic coil) type pickups, so you need to specify at time of ordering.

If you also buy the basic wiring harness for the TCIP4 (multi pin plug with wire tails pre-fitted), it saves a bit of fiddly work crimping wires onto the connectors and inserting them into the plug. That's especially handy if you don't have a crimping tool for the small connectors in the plug. If you buy the pre-wired harness, I'd suggest you remove any wires that you don't use to make the installation tidier. The cable connectors are easily removed from the plug with a suitable pointy tool to release the little catch that holds them in.

The guys at Ignitech are pretty helpful. They'll tell you what you need. They've done systems for Laverdas before.

Alternatively, you could buy Red's plug-and-play ignition upgrade kit for 120° Laverda triples. It consists of Hall pickups and rotor, and an Ignitech module pre-programmed for your bike. All components are very nicely made, and it comes with comprehensive instructions.
You can contact Red via the forum (redax5) https://www.laverdaforum.com/xf/members/39/
or Facebook https://www.facebook.com/people/Redax-Laverda/100063710341535/
 
Dell'Orto slides wear more than the bore of the carbs, so replacing just the slides refreshes the carb but eventually, bore wear will be a problem.
Be aware that new off the shelf Dell'Orto slides need a bit of modifying on the tick over screw ramp to be compatible with more recent carb bodies.

Paul
 
Dellortoman said:
The unit you need is a 4-channel version of their TCIP4 (they come in 2 and 4 channel versions). Just tell them what it's for and they'll pre-load it with suitable software.

Also tell them what pickups you're using. Their units use different internal hardware (or firmware?) for Hall pickups than they do for VR (magnetic coil) type pickups, so you need to specify at time of ordering.

If you also buy the basic wiring harness for the TCIP4 (multi pin plug with wire tails pre-fitted), it saves a bit of fiddly work crimping wires onto the connectors and inserting them into the plug. That's especially handy if you don't have a crimping tool for the small connectors in the plug. If you buy the pre-wired harness, I'd suggest you remove any wires that you don't use to make the installation tidier. The cable connectors are easily removed from the plug with a suitable pointy tool to release the little catch that holds them in.

The guys at Ignitech are pretty helpful. They'll tell you what you need. They've done systems for Laverdas before.

Alternatively, you could buy Red's plug-and-play ignition upgrade kit for 120° Laverda triples. It consists of Hall pickups and rotor, and an Ignitech module pre-programmed for your bike. All components are very nicely made, and it comes with comprehensive instructions.
You can contact Red via the forum (redax5) https://www.laverdaforum.com/xf/members/39/
or Facebook https://www.facebook.com/people/Redax-Laverda/100063710341535/
Click to expand...
Thanks for the info, is there any benefit to be found from replacing a working MotoWitt system?
 
Paul Marx said:
Won't the Topham gear as posted by Piet do the job?
Paul
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Sorry Paul, have been traveling throughout Europe since 1/9. I don't know about 3Cs, the problem on RGSs is that Red's angled inlet manifolds - worthwhile to keep the Mikunis at a reasonable angle - disallow use of the stock rubbers to the airbox, it makes for a strange pair of angles. Thus I use nice, big, Ramair filterpods as recommended by Keith N. Straight manifolds would have the RSs too close to their max angle spec.

But I highly recommend the switch; the Miks are nicer instruments and work significantly better. I also swapped the stock PHM40s on my Moto Guzzi with a pair of Mikuni HSR42s, same wonderful difference.

Red's also making me a pair of RSs for my SF2 project.
 
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