Thank OldJohnno for reminding me, I've gathered various RZ carbs, and some have a black coating on the carb slides. I hadn't seen this coating on a carb before, and the local carb spares supplier (Ian Williams Tuning, a karting supplier) hadn't seen it either, thought it was something someone had applied to take up clearance or as a performance aid. It feels a bit "teflonny".
Anyone got any ideas?
Looks original to me.
Carb slide coatings
Carb slide coatings
Ex UK, now in Adelaide. LC250/350. DT175. Shed full of sh1t in the vague form of dismantled rusty RD’s and RZ’s.
Re: Carb slide coatings
Mikuni flat slide stuff - TM, TMX, HSR etc - is hard anodised black, maybe this is something similar. It's quite possibly original; the OEMS carbs were often specced differently to the aftermarket carbs of the same type.
I liked the old VMs with the chromed brass slides - smooth as silk.
A bit off-topic but I tested some carbs a few weeks ago and found that a 38mm TMX flowed practically the same (211 vs 218cfm @ 1.5"hg) as the old 40mm VM. I still think the VM is hard to beat as an all-rounder.
I liked the old VMs with the chromed brass slides - smooth as silk.
A bit off-topic but I tested some carbs a few weeks ago and found that a 38mm TMX flowed practically the same (211 vs 218cfm @ 1.5"hg) as the old 40mm VM. I still think the VM is hard to beat as an all-rounder.
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2TInstitute
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Re: Carb slide coatings
What ever the coating is it never lasts for long. My beloved Dellorto's use annodised and chromed slides
Re: Carb slide coatings
Delirtos? What ae they on?
Ex UK, now in Adelaide. LC250/350. DT175. Shed full of sh1t in the vague form of dismantled rusty RD’s and RZ’s.
Re: Carb slide coatings
I can't comment on the nature of the black OEM slide coatings (e.g. Mikuni TM etc.), but see my reply to the piston coatings topic (viewtopic.php?f=22&t=2083). Although I've never had it done to a carb slide, I believe that the HPC DF1 coating is suitable. As the coating attracts oil, it should (theoretically) prevent the slide from sticking.
Regards,
James
Regards,
James
Re: Carb slide coatings
AFAIR, the black coated slides were introduced for the 2nd series/`85 model RZ's,
& for sure - it is def' not the same material as on flat slides..
I've had a bunch of 'em, both as they came on original bikes, & as spare parts..
& the RZ coating seems soft-wearing/matt-finish compared to the F-S's..
VM cylindrical slide carbs will flow more smoothly if you radius-fill the underside of the slide, with fuel-proof expoxy..
..or fancy 'UFO' stuffers, if you like to spend..
( same applies to flat slides, but they need less fillin' around the needle orifice)..
The improved venturi-effect is shown by having to go down in pilot jet sizing, & in superior throttle response/fuel economy..
& for sure - it is def' not the same material as on flat slides..
I've had a bunch of 'em, both as they came on original bikes, & as spare parts..
& the RZ coating seems soft-wearing/matt-finish compared to the F-S's..
VM cylindrical slide carbs will flow more smoothly if you radius-fill the underside of the slide, with fuel-proof expoxy..
..or fancy 'UFO' stuffers, if you like to spend..
( same applies to flat slides, but they need less fillin' around the needle orifice)..
The improved venturi-effect is shown by having to go down in pilot jet sizing, & in superior throttle response/fuel economy..
Re: Carb slide coatings
To put the historical timeline together, my bikes are 83/84 and an 85, the carbs I've looked at are early RZ ones, not powerjet carbs. One set is from a Canadian 350.
For me this is curiosity, I'm not practically concerned unless I have to replace parts due to wear, but the variability is curious.
Interesting how many different ways a slide can be treated.
For me this is curiosity, I'm not practically concerned unless I have to replace parts due to wear, but the variability is curious.
Interesting how many different ways a slide can be treated.
Ex UK, now in Adelaide. LC250/350. DT175. Shed full of sh1t in the vague form of dismantled rusty RD’s and RZ’s.
Re: Carb slide coatings
Lots of aftermarket stuff these days for Banshee ATV's & the like BRG...
See here for some Mikuni carb CFM flow comparos.. http://www.aaenperformance.com/snow_carb.asp
I have found that certain Polaris snowmobile applications use common Mikuni brass..
.. but retail them quite a bit less pricey than bike parts generally go for..
ie, SLP performance in the US sells 'Polaris' Mikuni needle jets for $US 4.99 & needles for $US 1.99 each..
See here for some Mikuni carb CFM flow comparos.. http://www.aaenperformance.com/snow_carb.asp
I have found that certain Polaris snowmobile applications use common Mikuni brass..
.. but retail them quite a bit less pricey than bike parts generally go for..
ie, SLP performance in the US sells 'Polaris' Mikuni needle jets for $US 4.99 & needles for $US 1.99 each..