hrc tap mod
Forum rules
Please can you post items for sale or wanted in the correct For Sale section. Items / bikes for sale here will be removed without warning. Reasons for this are in the FAQ. Thanks
Please can you post items for sale or wanted in the correct For Sale section. Items / bikes for sale here will be removed without warning. Reasons for this are in the FAQ. Thanks
-
- Settled in member
- Posts: 92
- Joined: Fri Jan 09, 2009 11:04 am
Re: hrc tap mod
Pardon my ignorance, but why does the dry break help?
- superlite
- Site Supporter
- Posts: 748
- Joined: Wed Apr 30, 2008 11:52 pm
- Bike owned: TLS, LB80 x 2
- Location: Australia
- Contact:
Re: hrc tap mod
If you stick a dry break (quick release) between the carbs and fuel tank, you know your HRC modded tap isn't going to piss in your engine.
But that only applies if you remember to disconnect the dry break when you're not using the bike
I use a CPC QR connector - they do the trick, but the o-rings are rubbish.
But that only applies if you remember to disconnect the dry break when you're not using the bike

I use a CPC QR connector - they do the trick, but the o-rings are rubbish.
'Take it to the Back'
- skinnydog0_0
- NWAA Supporter
- Posts: 1212
- Joined: Tue Apr 20, 2010 9:07 pm
- Bike owned: Penny Farthing
- Location: Pembrokeshire West Wales
Re: hrc tap mod
I had some trouble with my HRC tap mod, yesterday and today
I couldn't get the bike started and thought it was the battery, it was almost going with the choke on then flooding and not starting.
I tried to jump it off the car, and it started let it tick over to warm up, then it struggled and died.
I took the tank off and turned the tap to on, and nothing, turned it to reserve and nowt.
I put a tube on the vacume take off and gave a sharp suck and i could hear the diaphram move, then hey presto gogo juice.
Has anyone else had this happen?
If yes how do you sort it?
Cheers

I couldn't get the bike started and thought it was the battery, it was almost going with the choke on then flooding and not starting.
I tried to jump it off the car, and it started let it tick over to warm up, then it struggled and died.
I took the tank off and turned the tap to on, and nothing, turned it to reserve and nowt.
I put a tube on the vacume take off and gave a sharp suck and i could hear the diaphram move, then hey presto gogo juice.
Has anyone else had this happen?
If yes how do you sort it?
Cheers
- CMSMJ1
- Moderators
- Posts: 7152
- Joined: Thu May 01, 2008 9:42 am
- Bike owned: NC30-No9
- Location: Chesterfield, United Kingdom
Re: hrc tap mod
Is this bike actually suffering from lack of fuel or poor fuelling/setup?
@skinny - why not run the vacuum hose?
@skinny - why not run the vacuum hose?
IMPERATOR REX ANGLORUM
The V4 is the law..
NC30 - No9 - my old mate
The V4 is the law..
NC30 - No9 - my old mate
- skinnydog0_0
- NWAA Supporter
- Posts: 1212
- Joined: Tue Apr 20, 2010 9:07 pm
- Bike owned: Penny Farthing
- Location: Pembrokeshire West Wales
Re: hrc tap mod
I think it was a lack of fuel (originally). When it's flat out in 5th and 6th when the motor was really revving, it struggled, i thought it was the vacume hose collapsing so got a new one, and tried it but the same thing. i did the HRC tap mod, and it seemed to solve the issue. No probs in 5 and 6 when flat out.CMSMJ1 wrote:Is this bike actually suffering from lack of fuel or poor fuelling/setup?
@skinny - why not run the vacuum hose?
Then i blew that engine up, and now have the mongrel 30/35 engine in with a bit of home porting and 120 jets.
I have run the new engine a few times, not really flat out but given it a good go, and checked the plugs, lovely biscuit brown in all 4 cylinders.
then this starting issue.
I think the A/F is about right, but i might just put the tap back to standard and see what happens.
I may have been barking up the wrong tree from the start it might have been something else, and the fuel tap mod was just a coincidence

- Cammo
- Site Supporter
- Posts: 4505
- Joined: Thu May 01, 2008 12:35 am
- Bike owned: NC30
- Location: Melbourne, Australia
Re: hrc tap mod
I don't think you should have a diaphram in there if you've done the hrc mod??skinnydog0_0 wrote:I had some trouble with my HRC tap mod, yesterday and today![]()
I put a tube on the vacume take off and gave a sharp suck and i could hear the diaphram move, then hey presto gogo juice.
"It's just a ride" Bill Hicks
- Drunkn Munky
- Site Supporter
- Posts: 6313
- Joined: Thu May 01, 2008 9:37 am
- Bike owned: NC30 MC21 TZR FZR GSXR RG MITO
- Location: Kent
Re: hrc tap mod
At what rpm and speed is it strugling at?
- skinnydog0_0
- NWAA Supporter
- Posts: 1212
- Joined: Tue Apr 20, 2010 9:07 pm
- Bike owned: Penny Farthing
- Location: Pembrokeshire West Wales
Re: hrc tap mod
Sorry Cammo, it's the plastic disc in there, not the diaphram. Should that plastic bit still be in there?Cammo wrote:I don't think you should have a diaphram in there if you've done the hrc mod??skinnydog0_0 wrote:I had some trouble with my HRC tap mod, yesterday and today![]()
I put a tube on the vacume take off and gave a sharp suck and i could hear the diaphram move, then hey presto gogo juice.
- skinnydog0_0
- NWAA Supporter
- Posts: 1212
- Joined: Tue Apr 20, 2010 9:07 pm
- Bike owned: Penny Farthing
- Location: Pembrokeshire West Wales
Re: hrc tap mod
Hi DM, it seemd to have stopped the struggling since i did the tap change. That was on the standard engine. Since then i have a vfr/rvf mongrel engine, and this seems to rev out fine in each gear.Drunkn Munky wrote:At what rpm and speed is it strugling at?
On the original engine it was struggling at 12.5k to the redline in 5th and 6th.
- superlite
- Site Supporter
- Posts: 748
- Joined: Wed Apr 30, 2008 11:52 pm
- Bike owned: TLS, LB80 x 2
- Location: Australia
- Contact:
Re: hrc tap mod
Yeah, that's right. There should be the plastic disc and a small rubber diaphragm - the main (large) diaphragm is discarded with the HRC mod.skinnydog0_0 wrote:Sorry Cammo, it's the plastic disc in there, not the diaphram. Should that plastic bit still be in there?
'Take it to the Back'