Carb talk

Can I just say in my defence: the bike is running well, this is just a tiny tweak.  :D
 
I'm on a guilt trip because I know I should do the needles 'while I'm at it', but I ain't gonna.  :D
 
I have supported my local bike shop and got one locally. Added bonus I get to ride the bike this weekend and not wait for it to be shipped from wherever to Australia.

However that is a really good price, if I had seen it today I would of bought from stein dinse.

I will get a couple more and stand in the naughty corner.



 
Well I've got a lovely idle now with the mixture screws exactly 1 1/2 turns out, and pickup seems good, although the throttle action is still horrible cos of the pumps.  Moving the needle to the centre notch (standard) I think was not a good move as it seems fluffier now on the needle.  Will move the needle to the top notch (back to the way it was), should be OK for the time being.

Also found I had two long and one short snorkel between the carbs and airbox, think it should be one long and two short.  Ho hum.  Still, it passed the MOT today no problems.  Made the mistake of riding down to the shop for the test sans earplugs.  Bad move, it really is a much nicer ride with earplugs in, rattly old heap that it is.  :D
 
So what else did you do? Change the pilot jets? Or just adjust the mixture screws?
We need to know!  :D
 
Just changed the pilots to 58s and adjusted the screws out about 1/4 of a turn to 1 1/2 turns out.  Checked and adjusted the float heights.  The fact that the mixture screws were turned in a little suggests to me that 65s are a little rich for this bike.

Am going to drop the needles a notch to go back to the way it was for the main circuits.

IMHO one of the worst aspects of these carbs is the monstrously heavy pull cos of the pumper mechanism.  The pump arms coming on to the ramps can really be felt and this really doesn't help around town.  I did take the arms out of my last bike which helped the action a lot, but you probably shouldn't for good response.

Mikunis only have one pump (at least the way Red puts them together) although I don't know wether the fuel is fed to the other carbs.  Maybe I could take two of the pumps off my Dells to help the throttle action? >:D :o
 
Just snip off about a 1/4 of each throttle spring, Reggie.

Almost as light a pull as Mikkies. :D  In fact, I removed one of the 2 return springs on my Mikunis for an even lighter pull!

The single Mikuni pump has connecting tubes to the other carbs.

piet
 
They've already been snipped Piet, although by how much I don't know. 

The poor action seems to be a result of the initial lift of the pump arm up the ramp- that's what it feels like anyhow.

My Miks had a very light action- no problemo as I had a push-pull action on the throttle with two cables.

I have to do things in order though- this is a small issue really- I'll enjoy the bike until the end of the season and then have a looksee at the inside of the donk and maybe find out what all the rattling is about. :D

Shouldn't really complain really, the motors shagged and it still easily pulls 220kph (on private roads, of course)
 
While on the subject of Mikunis and Dellortos, Im almost certainly going to be removing my Happy Mikunis RS38's and fitting some Dellortos..
Im not relishing the work involved, the cost, the engineering and the final results, but for sure it will end up on the dyno, so will be interesting to see what effect it has overall.

Will have more questions, but considerations will be MPG, performance, flat spot, fit under spine, with raised engine. Cost, capacity to bore them out to 38 ?  Throttle weight, currently like PIets its on one return spring and is light as light can be..

Any pointers would be welcome, are PHF36's the same body as 32's, is it hard to rebush the throttle tops..?

Rob
 
Hey Rob, are you scared by the power your bike puts out or what is the reason for changing back?  :D So - in "De-tuning Mode", eh?  :LOL:

Honestly: will be really interesting to see how they work on your engine. Bet Top end is not the biggest issue (though there will be a drop of some HP), but acceleration and throttle response will make you think...

PHF32 and PHF36 share the same body. If you want 38, go for some Guzzi Carbs, they have PHM 38 or PHM 40 sometimes. 38 is hard to come by... Boring out the 36 to 38 is no good Idea, as the slider is 38mm and that means it will clapper quite as much as your flat sliders, mabe more. And it might be dangerous as the slider could stick in the carb...
 
Rob, Stefan,

Rebushing is quite easy, but you need either new or unworn spindles to achieve a decent result.

As Stefan points out, there is enough room in the spindle housing to place the bush/es in a different position so they carry an unworn portion of an old spindle.

Maintenance-free Glyco bushes do not wear very well in this application, I go for oil-soaked sinter bronze bushes as supplies of the original steel-backed split bushes have dried up recently.  They are a bugger to ream them in line though.

I once replaced the bushes with needle bearings and the spindles with a one-piece solid spindle passing through all 3 carbs, Mikuni style.  Worked quite well, only synchronising was a royal pita!

piet
 
Thanks Guys, I'll keep this in mind. Have a worn set of 32's off my Jota, so it seems I can do something with them.....even if I only reuse the tops and buy new carbs..
 
Hum, well, 58s...  Definitely improved the low down response, but I did notice a couple of pops now and again, indicating leanness.

BUT then I found that one of the carb to airbox rubbers wasn't fitting properly- AAAAAARGHHH!!!! why not???-  which may be the reason the DPO used mismatched ones.  Can't really move the airbox up much (gap is at the bottom) Fahn cahn.

Anyway, reckon 60 pilots and a properly sealing airbox would do the trick. ::)

Do I need the bike for anything important this weekend?
 
Rob why change from Mikuni to Dell Orto , if you make change from Mikuni to Keihin FCR i could understand, or is it becouse of some racing rules .

In other thred you wirte something about buliding engine over 1400ccm, is it pasible with Laverda engine ? .
 
Hi Romeo

Simple reasoning. No classic type racing series over here will accept Flatslides  (thunderbikes excepted). Im going to do something with the bike this year hence ultimately the change over.

The engine size was a typo error, I meant to say 1144 not 1444 :) had you thinking though  :D :D
 
Robjota said:
Hi Romeo

Simple reasoning. No classic type racing series over here will accept Flatslides  (thunderbikes excepted). Im going to do something with the bike this year hence ultimately the change over.

The engine size was a typo error, I meant to say 1144 not 1444 :) had you thinking though  :D :D
Click to expand...

Same thing was here but now flat sides are acepted , maybe is Keihin CR way to go i have them on Bakker it is Kawasaki 1200 engine with Keihin CR 33 they also have 38 or biger .

1444ccm Jota this would be interesting ,
 
Reggie3cl said:
Hum, well, 58s...  Definitely improved the low down response, but I did notice a couple of pops now and again, indicating leanness.

BUT then I found that one of the carb to airbox rubbers wasn't fitting properly- AAAAAARGHHH!!!! why not???-  which may be the reason the DPO used mismatched ones.  Can't really move the airbox up much (gap is at the bottom) Fahn cahn.

Anyway, reckon 60 pilots and a properly sealing airbox would do the trick. ::)

Do I need the bike for anything important this weekend?
Click to expand...

Better get that carb to airbox gap fixed would hate to see the rain on sunday flood the motor :D

                                                                  Dave
Better get that cab to airbox
 
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