small issue

15-08-2020, 10:16 PM

Hi to everyone, this is my first post and I'm asking for help.
I have completely rebuilt my M750 into a cafe racer. The small issue im having is it stutters when in top gear around 65mph. Everything electrical is new and it revs as it should in all other gears. I think its a fueling issue. Has anyone removed the vacuum type fuel pump and fitted a electric pump, if so which one have you used ?

Any thoughts would be greatly received

Mr Gazza · 15-08-2020, 10:38 PM

The vacuum pumps can be rebuilt with new parts, but they usually cause priming problems and therefore poor starting rather than high speed supply.

If you have done away with the grey triangular plastic pods in the frame either side, it can upset the running at certain speeds, and also bizarrely at certain angles of side winds.

Oh, and welcome to the club btw..

15-08-2020, 10:49 PM

Thanks Gazza, that was a really good guess. i still have them so ill put them on an go for a ride tomorrow, fingers crossed as its a real issue when overtaking.

Mr Gazza · 15-08-2020, 11:13 PM

Their function is to allow the vent pipes from the carbs to end in still air, so hopefully you can remember which pipes it was that were in the pods originally, as I couldn't help you with that I'm afraid.
Good luck, hope it works.

16-08-2020, 05:51 AM

Quote:

Originally Posted by craig2494

Hi to everyone, this is my first post and I'm asking for help.
I have completely rebuilt my M750 into a cafe racer. The small issue im having is it stutters when in top gear around 65mph. Everything electrical is new and it revs as it should in all other gears. I think its a fueling issue. Has anyone removed the vacuum type fuel pump and fitted a electric pump, if so which one have you used ?

Any thoughts would be greatly received

Hi Craig, sounds an interesting project, welcome aboard. You can always join us at our monthly meeting which will be starting again in September.....restrictions permitting of course. Look out for Manchester and north west post.

Would be great to see your bike .....and you of course

Flip · 16-08-2020, 10:17 AM

Welcome along- we need pictures but you’ll need a hosting site to post them here.

Yep I agree with Gazza’s suggestion of the grey pods- without them it can give a feeling if pulsing when on a steady cruising throttle.

Locating the tubes in some still air should cure it but you say it’s an issue when asking for more fuel when over taking which isn’t usually a symptom- is 65mph a bit slow for top gear on a 750?

mickj · 16-08-2020, 10:33 AM

Welcome to the forum Craig.

16-08-2020, 01:54 PM

Thank Chaps, Ive just fitted one of the grey pods(lost the other) but ive joined the both pipes into one to test it out the fix. Just been out and its perfect !!!

Thanks for the Advise and i will definitely meet up with you all, think i owe pint or two

Ill try and get a few pictures on this afternoon, I'm quite pleased with how its turned out.

I went to the super-bike factory in Macclesfield yesterday with a couple of mates and genuinely didn't see a bike i would have wanted instead. Though there was loads there in the new building.

Mr Gazza · 16-08-2020, 02:20 PM

Nice one..

I'm virtually teetotal but I accept chocolate Hobnobs..

If you want to ditch the pod(s) again all you have to do is find a location with still air for the ends of the pipes. I think others have done it, but I don't run carbs anymore, so I can't suggest a place.

You will do much worse than riding out to meet the North-West gang, they're a nice bunch as mis-fits go..

15-08-2020, 10:16 PM	#1
craig2494 Guest Posts: n/a	small issue Hi to everyone, this is my first post and I'm asking for help. I have completely rebuilt my M750 into a cafe racer. The small issue im having is it stutters when in top gear around 65mph. Everything electrical is new and it revs as it should in all other gears. I think its a fueling issue. Has anyone removed the vacuum type fuel pump and fitted a electric pump, if so which one have you used ? Any thoughts would be greatly received

15-08-2020, 10:38 PM	#2
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,964	The vacuum pumps can be rebuilt with new parts, but they usually cause priming problems and therefore poor starting rather than high speed supply. If you have done away with the grey triangular plastic pods in the frame either side, it can upset the running at certain speeds, and also bizarrely at certain angles of side winds. Oh, and welcome to the club btw.. __________________

15-08-2020, 11:13 PM	#4
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,964	Their function is to allow the vent pipes from the carbs to end in still air, so hopefully you can remember which pipes it was that were in the pods originally, as I couldn't help you with that I'm afraid. Good luck, hope it works. __________________ Last edited by Mr Gazza; 16-08-2020 at 09:45 AM.. Reason: Added a 'p' so you didn't try and put pies in the pods!

16-08-2020, 10:17 AM	#6
Flip Registered User Join Date: Mar 2010 Location: Beachtown Bike: M900 Posts: 2,188	Welcome along- we need pictures but you’ll need a hosting site to post them here. Yep I agree with Gazza’s suggestion of the grey pods- without them it can give a feeling if pulsing when on a steady cruising throttle. Locating the tubes in some still air should cure it but you say it’s an issue when asking for more fuel when over taking which isn’t usually a symptom- is 65mph a bit slow for top gear on a 750? __________________ You're perfect, yes, it's true- But without me you're only you!

16-08-2020, 10:33 AM	#7
mickj Registered User Join Date: Jun 2018 Location: Clevedon Bike: M1200s Posts: 565	Welcome to the forum Craig. __________________ Keep the rubber side down. Mick

15-08-2020, 10:49 PM	#3
craig2494 Guest Posts: n/a	Thanks Gazza, that was a really good guess. i still have them so ill put them on an go for a ride tomorrow, fingers crossed as its a real issue when overtaking.

16-08-2020, 01:54 PM	#8
craig2494 Guest Posts: n/a	Thanks Thank Chaps, Ive just fitted one of the grey pods(lost the other) but ive joined the both pipes into one to test it out the fix. Just been out and its perfect !!! Thanks for the Advise and i will definitely meet up with you all, think i owe pint or two Ill try and get a few pictures on this afternoon, I'm quite pleased with how its turned out. I went to the super-bike factory in Macclesfield yesterday with a couple of mates and genuinely didn't see a bike i would have wanted instead. Though there was loads there in the new building.

16-08-2020, 02:20 PM	#9
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,964	Nice one.. I'm virtually teetotal but I accept chocolate Hobnobs.. If you want to ditch the pod(s) again all you have to do is find a location with still air for the ends of the pipes. I think others have done it, but I don't run carbs anymore, so I can't suggest a place. You will do much worse than riding out to meet the North-West gang, they're a nice bunch as mis-fits go.. __________________