Author Topic: 750 K2 Strip & Rebuild - help please  (Read 8668 times)

Offline Trigger

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Re: 750 K2 Strip & Rebuild - help please
« Reply #135 on: June 27, 2022, 02:08:24 PM »
Cheers Graham. The passed couple of months I’ve been using the Sandcast as my go-to reference for the K2 rebuild (when in doubt), but alas that doesn’t have the pulley wheel. And tbh, I didn’t give it a thought…

So dang when you pointed out the gold passivate finish! (& thanks). Fixed now…

And yep, the acid wash… basically 30 secs in a weak solution followed by a distilled water rinse - ie not concerned wrt hydrogen embrittlement (which is fully covered in the plating manual)

They look perfect  ;) I only found out that they were alloy rivets when i got them back from the platers years ago in two parts and had to re-rivet them using old Land rover body rivets.
 

Offline Matt_Harrington

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Re: 750 K2 Strip & Rebuild - help please
« Reply #136 on: June 27, 2022, 05:25:31 PM »
Excellent plating. I bought a kit 15 years ago and have just unearthed it. If I can get my parts half as good as that, I'll be happy!
Matt
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Moto Guzzi T4 - 1981
Triumph 3T - 1946 - Now finished(ish)
Triumph 3T - 1947 (somewhat dismantled!)

Offline Oddjob

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Re: 750 K2 Strip & Rebuild - help please
« Reply #137 on: June 27, 2022, 09:58:54 PM »
If you unearth it then it won't work  ;D ;D

I'll get me coat.
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Offline Sesman

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Re: 750 K2 Strip & Rebuild - help please
« Reply #138 on: June 28, 2022, 05:59:22 AM »
Boom, boom. You ground that one out  :)

Offline Matt_Harrington

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Re: 750 K2 Strip & Rebuild - help please
« Reply #139 on: June 28, 2022, 09:44:47 AM »
If you unearth it then it won't work  ;D ;D

I'll get me coat.

Gawd!  :D :D
Matt
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CB400F 1976 - New project
Moto Guzzi T4 - 1981
Triumph 3T - 1946 - Now finished(ish)
Triumph 3T - 1947 (somewhat dismantled!)

Offline Lobo

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Re: 750 K2 Strip & Rebuild - help please
« Reply #140 on: July 01, 2022, 12:42:08 AM »
Bench carb set-up…

Know about the 3mm drill trick in initially setting the sliders - but which end of the carb to stick it in?!

If I use the engine manifold side (straight skirt, and from a previous SOHC post) I’m left with abouts 7mm of thread protruding above the adjuster lock-nut. This goes against my manual suggestions of 1-2mm, which was also what I had when I dismantled the carbs… (ie 1.5mm)

If, otoh, I go for the Airbox side (domed skirt) I do indeed get the 2mm free thread, but virtually closed throat on the opposite side. 

Cheers in anticipation….


Offline Oddjob

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Re: 750 K2 Strip & Rebuild - help please
« Reply #141 on: July 01, 2022, 01:02:50 AM »
It's meant to be a closed throat on the other side as this is how the carbs are at idle.
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Offline Lobo

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Re: 750 K2 Strip & Rebuild - help please
« Reply #142 on: July 01, 2022, 01:17:28 AM »
Cheers Ken. This fits with the 2mm (and my carbs @ dismantle) free thread spec, and suggests the drill goes in the domed skirt / airbox side. That however, seems to be in confliction with other posts I’ve read on this SOHC Forum.

Ho hum.. will go with your advice / the 2mm free thread spec.

Offline Oddjob

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Re: 750 K2 Strip & Rebuild - help please
« Reply #143 on: July 01, 2022, 02:16:09 AM »
Actually I may have it the wrong way round. IIRC the drill bit goes into the engine side as that the gap the carbs need to idle properly. The idea being that they are all the same gap when you fit them and you then adjust the idle speed correctly using the large screw on the linkage bar.

In the bottom pic it's the left hand carb which is orientated correctly for the drill bit.
« Last Edit: July 01, 2022, 02:18:54 AM by Oddjob »
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Offline K2-K6

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Re: 750 K2 Strip & Rebuild - help please
« Reply #144 on: July 01, 2022, 06:11:05 AM »
Actually I may have it the wrong way round. IIRC the drill bit goes into the engine side as that the gap the carbs need to idle properly. The idea being that they are all the same gap when you fit them and you then adjust the idle speed correctly using the large screw on the linkage bar.

In the bottom pic it's the left hand carb which is orientated correctly for the drill bit.

Agree with this to set on bench.

Initially set the threads as you want to match original Simon, then turn the "master" tickover screw to lift all the slides such that you can get the drill of choice underneath the #2 throttle slide like a feeler gauge just sliding fit. Now set the other three carb with that same drill as feeler gauge with their own threads to get parity. Once it slides concisely into all four you've equalled them as a set.

Now bring that "master" control back down to their closed/running position to set them ready to start the engine. 

Once it's up and running, don't reset the carb balance (it will be correct iif done accurately) and allow running in to be completed and then valve gaps etc to be confirmed/reset to specification (these gaps will affect vacuum reading and so shouldn't be relied upon during this period) then take a reading of vacuum if you need to quantify it.

It's an odd situation (often propogated by statement of "just needing a carb sync") but mechanical accuracy in setup will hold absolute technical priority over vac gauges if done with diligence.  It's primary function is to set the slides at parity for full power balance (this is not measured with vacuum gauges) with conditional low speed running as a side benefit of it.

Fine cylinder "tickover" balance is completed with individual airscrew optimisation in finally setting that smooth running. 

Offline Lobo

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Re: 750 K2 Strip & Rebuild - help please
« Reply #145 on: July 01, 2022, 10:02:37 AM »
Carbs finished - everything possible to be done… was done.

Thanks Nige - all makes perfect sense. The only remaining question is ‘how much’ gap to finally leave wrt the “closed / running position”…. 01mm, 0.5mm? I do have the original ‘thread remaining’ figures, and so indeed could roughly set this.

(To labour the perfect sense bit; I’m left bloody wondering why I bought a set of vacuum gauges 😂, though am indeed happy to leave ‘em in the cupboard!)

Many thanks,
Simon
« Last Edit: July 01, 2022, 10:06:12 AM by Lobo »

Online McCabe-Thiele (Ted)

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Re: 750 K2 Strip & Rebuild - help please
« Reply #146 on: July 01, 2022, 10:14:54 AM »
Wow the complete carbs look brilliant - factory fresh if you will - that's a lot of attention to detail.
« Last Edit: July 01, 2022, 03:52:36 PM by McCabe-Thiele (Ted) »
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Offline Lobo

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Re: 750 K2 Strip & Rebuild - help please
« Reply #147 on: July 01, 2022, 12:24:14 PM »
Cheers Ted, appreciated. It took a fair bit of time and effort - hoping it’s repaid in full!

Offline Sesman

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Re: 750 K2 Strip & Rebuild - help please
« Reply #148 on: July 01, 2022, 01:07:48 PM »
Do not fit those to a dirty, foul smelling motorcycle.

Offline Lobo

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Re: 750 K2 Strip & Rebuild - help please
« Reply #149 on: July 01, 2022, 01:36:55 PM »
…don’t worry!

 

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