Building a intake with a single mechanical TB from the 60's - Page 2 - SV650.org

gt alex · 21-12-20, 11:32 AM

I through myself a curve for a couple of days by not pressing to rear of the manifold all the way home. but I should be back on track now.

gt alex · 04-01-21, 11:17 AM

So after fixing the leak I could try some tuning and although better the rear cylinder was still dropping off below 2500 for 10sec then springing back to life for 5secs repeating.
Now running a balance tube that did improve things a bit stabilized the idle speed but below 2000 the rear cylinder would drop of and stay off.
Although I knew it wasn't ideal the throttle plate opens towards the front cylinder.
I spun the carby 180deg now opening towards the rear cylinder and idling at 1400rpm, pulling the front and rear plug both plugs had similar effect but the idle exhaust sound was not even.
So it looks like it will be worth making an adapter to run the throttle across the plenum.

gt alex · 10-01-21, 03:16 AM

I broke down on my test ride last week
I think I found the problem. I lost the vacuum plug I was using on a T piece on the hose to the petcock and in my impatience I used a screw to block it. But it did a bad job.
I found it using a hand vacuum pump,
Unfortunately we are in lock down again so I will test ride it Tuesday if restrictions are lifted.
The pump is pumping well cranking the engine.
I am thinking of fitting a relay and fuse for an electric pump incase it is needed on dyno day.
I need to rebook the dyno after the lock down.

yorkie_chris · 04-02-21, 10:58 AM

That's cool.

Although probably not going to do any better than the standard carbs, and definitely not than a pair of FCR's...

gt alex · 26-07-21, 08:43 AM

First dyno session was a success the single throttle body produced more torque than stock although peak was 1000 rpm lower so peak power was 62hp at 8800 and peak torque 44ft/lbs at 7000 at the wheels standard spec is 65hp at the flywheel.
The end result was reasonable but the mechanical throttle ended up mal adjusted and unable to open fully so I needed the recalibrate it, but I know there is more power to be had.
After going home I thought hard about what would correct the metering and after making changes it ran better but I wanted to get it as close as I can before another dyno session.

Got a Colortune today, it is magic.
I only used it on the rear cylinder the front is too awkward.
Its a spark plug with a window so you can see the colour of the combustion and check the mixture.
I put it on and idle was correct (not surprising there is a air corrector to get idle correct) from idle to 5000 was rich then from 5000 up was good all checked free revving on a stand.
So I adjusted the higher revs to be richer and then leaned the whole range to be correct.
Its such a good feeling when You can see the combustion colour as you build revs and it is all good.
The bike had been running well but I knew it needed tweaking and the Color tune made it so easy. Adjustment took only 15 minutes.

gt alex · 29-07-21, 11:38 AM

I was trying to source advice from the man that had the world patent (except us) and was the only legitimate manufacturer outside the U.S. Bob Henderson in Scotland.
I was saying, once I have this sorted best I can, I would like to try dual fish on the sv,

This is a extract of the relevant part of his reply,, Just thought I would share it as it may shed some light on why I am starting with the single throttle body.

"As to using "twins" there would have to be a VERY exceptional reason for doing so!
Rememer all our racing car successes and Championshiups were always on a "single".(from Nurberg Ring to Le Mans)
Most of the conventional reasons for using "twins" do not usually apply when using the "Fish" principle. Including some very awkward aero "set ups"."

gt alex · 04-08-21, 08:03 AM

A quick walk around
https://photos.app.goo.gl/4rgsTdoueyTLqam57

Trail to see what Honda tank looks like on the SV cafe racer

gt alex · 05-08-21, 02:35 AM

Just picked up some 6mm steal rod which I will use to make a skeleton for the base. Thinking of sliding the tank back 40mm if the lines look right and the hinge works, that will make the new design that is much simpler.
If I fit the air cleaner sideways, from the air cleaner forward will be air box and the rear all fuel. Makes for an easer build and probably more fuel capacity.

admin · 05-08-21, 07:39 AM

Looks good Alex, you might want to give your camera lens a clean.

Sent from my SM-T510 using Tapatalk

gt alex · 08-08-21, 03:33 AM

Getting there I think just 1cm (3/8") more drop over the seat and we are there I think, what do you all think am i missing something? I feels right

21-12-20, 11:32 AM	#11
gt alex Member Join Date: Jul 2019 Posts: 95	Re: Building a intake with a single mechanical TB from the 60's I through myself a curve for a couple of days by not pressing to rear of the manifold all the way home. but I should be back on track now.

04-01-21, 11:17 AM	#12
gt alex Member Join Date: Jul 2019 Posts: 95	Re: Building a intake with a single mechanical TB from the 60's So after fixing the leak I could try some tuning and although better the rear cylinder was still dropping off below 2500 for 10sec then springing back to life for 5secs repeating. Now running a balance tube that did improve things a bit stabilized the idle speed but below 2000 the rear cylinder would drop of and stay off. Although I knew it wasn't ideal the throttle plate opens towards the front cylinder. I spun the carby 180deg now opening towards the rear cylinder and idling at 1400rpm, pulling the front and rear plug both plugs had similar effect but the idle exhaust sound was not even. So it looks like it will be worth making an adapter to run the throttle across the plenum.

10-01-21, 03:16 AM	#13
gt alex Member Join Date: Jul 2019 Posts: 95	Re: Building a intake with a single mechanical TB from the 60's I broke down on my test ride last week I think I found the problem. I lost the vacuum plug I was using on a T piece on the hose to the petcock and in my impatience I used a screw to block it. But it did a bad job. I found it using a hand vacuum pump, Unfortunately we are in lock down again so I will test ride it Tuesday if restrictions are lifted. The pump is pumping well cranking the engine. I am thinking of fitting a relay and fuse for an electric pump incase it is needed on dyno day. I need to rebook the dyno after the lock down.

04-02-21, 10:58 AM	#14
yorkie_chris Noisy Git Mega Poster Join Date: Apr 2007 Location: Halifax/Leeds Posts: 26,645	Re: Building a intake with a single mechanical TB from the 60's That's cool. Although probably not going to do any better than the standard carbs, and definitely not than a pair of FCR's... __________________ Currently Ex Biker Now rebuilding a 63' fishing trawler as a dive boat

26-07-21, 08:43 AM	#15
gt alex Member Join Date: Jul 2019 Posts: 95	Re: Building a intake with a single mechanical TB from the 60's First dyno session was a success the single throttle body produced more torque than stock although peak was 1000 rpm lower so peak power was 62hp at 8800 and peak torque 44ft/lbs at 7000 at the wheels standard spec is 65hp at the flywheel. The end result was reasonable but the mechanical throttle ended up mal adjusted and unable to open fully so I needed the recalibrate it, but I know there is more power to be had. After going home I thought hard about what would correct the metering and after making changes it ran better but I wanted to get it as close as I can before another dyno session. Got a Colortune today, it is magic. I only used it on the rear cylinder the front is too awkward. Its a spark plug with a window so you can see the colour of the combustion and check the mixture. I put it on and idle was correct (not surprising there is a air corrector to get idle correct) from idle to 5000 was rich then from 5000 up was good all checked free revving on a stand. So I adjusted the higher revs to be richer and then leaned the whole range to be correct. Its such a good feeling when You can see the combustion colour as you build revs and it is all good. The bike had been running well but I knew it needed tweaking and the Color tune made it so easy. Adjustment took only 15 minutes.

29-07-21, 11:38 AM	#16
gt alex Member Join Date: Jul 2019 Posts: 95	Re: Building a intake with a single mechanical TB from the 60's I was trying to source advice from the man that had the world patent (except us) and was the only legitimate manufacturer outside the U.S. Bob Henderson in Scotland. I was saying, once I have this sorted best I can, I would like to try dual fish on the sv, This is a extract of the relevant part of his reply,, Just thought I would share it as it may shed some light on why I am starting with the single throttle body. "As to using "twins" there would have to be a VERY exceptional reason for doing so! Rememer all our racing car successes and Championshiups were always on a "single".(from Nurberg Ring to Le Mans) Most of the conventional reasons for using "twins" do not usually apply when using the "Fish" principle. Including some very awkward aero "set ups"."

05-08-21, 02:35 AM	#18
gt alex Member Join Date: Jul 2019 Posts: 95	Re: Building a intake with a single mechanical TB from the 60's Just picked up some 6mm steal rod which I will use to make a skeleton for the base. Thinking of sliding the tank back 40mm if the lines look right and the hinge works, that will make the new design that is much simpler. If I fit the air cleaner sideways, from the air cleaner forward will be air box and the rear all fuel. Makes for an easer build and probably more fuel capacity.

05-08-21, 07:39 AM	#19
admin John T Mega Poster Join Date: May 2003 Location: Shrewsbury, Shrops, UK Posts: 2,455	Re: Building a intake with a single mechanical TB from the 60's Looks good Alex, you might want to give your camera lens a clean. Sent from my SM-T510 using Tapatalk __________________ Admin for this forum and the main site. John@sv650.org

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
mechanical help?	2hys	SELKENT	5	15-11-09 11:05 AM
Mechanical Help Please!	Noble Ox	SV Talk, Tuning & Tweaking	59	08-11-09 03:15 PM
Car mechanical questions	the_lone_wolf	Idle Banter	17	20-03-08 04:52 PM
Mechanical Aptitude	Dicky Ticker	SV Talk, Tuning & Tweaking	2	15-04-07 07:48 AM
Mechanical Advice.....	SoulKiss	Bikes - Talk & Issues	4	07-12-06 09:59 PM