MK3 carb boots :-(

jimbo · Feb 16, 2019

I struggled to get the rubber boots fit on the carbs and plastic air box on the JPN( same as a MK3 almost) I would have rather installed the carbs! What a PITA Then I noticed it looks like I installed the threaded rings on the carbs the wrong way around. Doing it that way seem to give me more rubber between the carbs and air box to work with. I thought about removing the air box door and filter element and threading my hand into the air box to work the rubbers into their grooves but that seemed to be a non starter. Any tricks putting these silly things on?

dynodave · Feb 16, 2019

Once you have the process down, it is fairly easy.
For me there is only one way...It is considering you have an "S" with the pipes in the way,
or have the 74 air cleaner plate with the inner snorkle.
I always install carbs (w/adaptors) and air cleaner complete.
Always from the right side of the machine,
Use new or good soft boots,
lube boot with silicone grease,
put LH boot on... first on carb ring,
make sure boot "flat" faces middle,
with your special 8-10" long thin small flat screwdriver(mine is Xcelite R186)...push boot groove into plastic box aperture,
make sure flat is still in the middle.
Now repeat for RH boot.
Will easily take less than 10 minutes start to finish.
Takes longer if sober....

N0rt0nelectr@ · Feb 16, 2019

The boots for a Mk2A and a Mk3 are different from the earlier ones.
John in Texas

dynodave · Feb 16, 2019

N0rt0nelectr@ said:
The boots for a Mk2A and a Mk3 are different from the earlier ones.
John in Texas

For me there is only one way
I have 2 MKIII and several regular commando and I use the same process using their respective correct part for all of them.

dynodave · Feb 16, 2019

In 1995 I rode my combat with my new repop BRG fastback bodywork to the 1995 INOA Grape Country Ralley in NY. One evening, guys were talking about this very topic. So despite my belly full of beer, I showed them the process I had developed by trial and error and now use exclusively to this day. I yanked them off, and put them right back on. A lot less than 10 minutes...but the boots must be soft and silicone lubed.
Poking and proding the rubber into the air cleaner flat plate or plastic air box is where the practice comes in. Finally the AH HA skill accomplished moment will come. ezzy peezy from then on.

jimbo · Feb 16, 2019

should I take the rubbers back off and reverse the threaded rings so the large parts are hard up against the carbs ? As shown in the above drawing? Right now they are not screwed on tight,installed backwards in order to turn the rubbers a little with them tight on the rings. It appears one secret is the rubber lube.

lazyeye6 · Feb 16, 2019

Ah Ha! Silicone lube
Then the Johnny Cash song, "Get Rhythm"
True, do it couple of times and it comes to you.

Another thing to consider is being quite sure your carbs are installed
and dialed in correctly. No point in aggravating yourself repeatedly.

OR? A Mikuni?

dynodave · Feb 16, 2019

jimbo said:
should I take the rubbers back off and reverse the threaded rings so the large parts are hard up against the carbs ? As shown in the above drawing? Right now they are not screwed on tight,installed backwards in order to turn the rubbers a little with them tight on the rings. It appears one secret is the rubber lube.

Yes put them on correctly, and fairly tight. The lube will allow the tweek to put the flat to the middle. I think the silicone will also help to protect the inside of the boot from e-10 vapor and slow down the eventual hardening.
Get the "far side" started with one poke. Get about 90-120 degrees engagement started.
Do little bits of engagement alternating top and bottom . If done equally then final part of boot to be pushed into filter housing is closest to you and will be the flat (on left hand rubber).

Doing RH boot...Repeat like above but ....first engagement into filter housing will be RH boot flat against previous LH boot flat.

jimbo · Feb 16, 2019

lazyeye6 said:
Ah Ha! Silicone lube
Then the Johnny Cash song, "Get Rhythm"
True, do it couple of times and it comes to you.

Another thing to consider is being quite sure your carbs are installed
and dialed in correctly. No point in aggravating yourself repeatedly.

OR? A Mikuni?

the bike started and ran after a very few minor adjustments after a carb cleaning and rebuild, I was happy. I will tackle the rubbers again and flip the rings tomorrow

NortonMKIIA850 · Feb 17, 2019

Screw the rings onto the carbs per the diagram. The rings have slots in their outer circumferences: with a bit of lube or without (I don't bother), first prod a boot into the airbox so that it's fully seated, then start the boot over the carb ring so that the lip 'snags' in one of the slots. Then rotate the boot, using the slot in the carb ring to feed the lip of the boot fully over the carb ring, until there's only a bit of the boot left unseated – the last bit pushes over the carb ring easily. The boots are properly installed when the flats on their airbox-end circumferences face each other. It's the rotating bit that does it for me. HTH

jimbo · Feb 17, 2019

got them damn things on! With a combination of your techniques . I applied silicon, on the rubbers , they slide easier but popped off easier too. I tried several times that way. Then I came up with zip tying the rubbers to the rings off the carb,( they popped off otherwise) screwing the assembly onto the carb and working the rubber into the air box slot at the same time. I marked the rubbers and the rings when tightened for proper orientation. Photos below.

NortonMKIIA850 · Feb 18, 2019

An interesting approach – I find it much harder to seat boots in the airbox when they're already attached to the carbs! I can't help thinking a simpler approach is quicker and easier, but I have to admire your inventiveness, and the main thing is you got it done! Good for you.

By the way, can I ask what that chrome or stainless thing is, projecting from behind the Z plate and over the gearbox?

jimbo · Feb 18, 2019

thanks, worked for me, JPN fairing bracket in cast aluminum

NortonMKIIA850 · Feb 18, 2019

Oh of course, thanks!

Steves · Feb 21, 2019

Some interesting stuff. I am with Dynodave and Elton John, judicious use of lube eases the way. My technique which is probably not the the best is to take the carbs off and reinstall the rubbers first then the carbs (and manifolds together), it's a bit fiddly but my svelt farmer fingers and the modified allen key we all have seem to manage.