[lonchovalle]

Thanks buddy, actually it works pretty good with the centrifugal advance in the dizzy and no need of the vacuum advance, you are right, the idea was to use the nipples for the vacuum advance but there is no issues at all right now, but i’ll do it in the future.

 

[lonchovalle]

The last adjustments and definitive setup:

Engine 1.8 8V, CBR 900RR carbs, stock ignition, centrifugal dizzy with vacuum advance unpluged, mechanical fuel pump with fuel restrictor to carbs.​
Number of test	slow jet size	idle screws turns out	main jet size	Needle jet height	Results
1	40	3	155	standard	Good idle, no throttle response and low power with bad revving, running hot and too lean
2	40	3	165	standard	Good idle, no throttle response and low power with bad revving, running hot and too lean
3	40	3	180	standard	Good idle, no throttle response and super bad revving and no power at all, really bad MPG, super black spark plugs with carbon fouling, running super rich
4	50	1.5	165	standard	Bad idle, better throttle response and better revving, feels a bit of power, bad MPG, black spark plugs with carbon fouling, running rich
5	50	1.5	155	standard	Bad idle, better throttle response and better revving, feels a bit of power, bad MPG, black spark plugs with carbon fouling, running rich
6	50	1	155	standard	Better idle, better throttle response and revving, feels more power, better MPG, spark plugs with light carbon build up, running rich
7	50	3/4	150	standard	good idle, good throttle response and revving, feels more power, better MPG, spark plugs with light carbon build up, running rich yet
8	50	1/2	150	standard	good idle, good throttle response and revving, can feel the power, nice MPG, spark plugs with very light carbon build up almost unperceptible, running almost normal
					At this point i get an AFR narrow band gauge, the numbers at idle was oscilating between 14.3-14.6, at WOT oscilating between 12.3-13, maybe use a 140 mains play with needle heights and see what happens
9	50	1/2	140	standard	good idle, good throttle response and revving, ~25 MPG, spark plugs with no carbon build up, running normal, 14.3-14.6 at idle, 13-14 at WOT
					After around 200 miles of driving the spark plugs shows very little carbon build up may be caused by the combination of slow and main jets at middle range throttle so the slow jet was replaced with a 45 size
10	45	2 1/2	140	standard	Not yet, check pending
					After driving around 100 miles take out the plugs and it seems OK no carbon build up at all, wet or oil. I think i get the correct AFR mixture, got a decent MPG (~4.5 gal in 100 miles) so i decide use this setup permanently.​
11	45	3 1/8	140	standard	Change the mixture in the idle jet by using the idle screw (3 1/8 turns out) after experimented little power at low RPM, issue was corrected

 

[lonchovalle]

Recently take the plugs to check it and looks good for me after 750 miles

 

[Jettaboy1884]

Looks like you have a solid approach and made a lot of headway, very nice!

A couple questions: Do you have a wideband O2 sensor/gauge to help you with the adjustments, or are you running purely on that narrowband? I have heard that narrowbands are unfortunately just not versatile enough for this kind of tuning.

Can you explain your fuel supply setup from tank to carbs? It seems a bit complicated in the bay.

I never took my Mk2 bike carb setup as far as you've gone with yours (I sold it before dialing it in) but I learned that it was easy to over-complicate things. Going from a CIS system, I only had the in-tank "lift" pump moving fuel to the bay. It fed a normal in-line filter, and then another filter with a small second output nipple (intended to purge air) which would return excess fuel to the tank. My thought was that it would keep the in-tank pump from dead-heading when the carb float valves were closed.

With a fuel pressure gauge after that second filter, the feed line to the carbs still saw a steady 3 psi.

 

[lonchovalle]

Do you have a wideband O2 sensor/gauge to help you with the adjustments, or are you running purely on that narrowband? I have heard that narrowbands are unfortunately just not versatile enough for this kind of tuning.

As you points, initially i did try to tune the AFR with the narrowband, but it did not seems to be precise, so i decided to use the old school method trial and error by reading the spark plug at different RPMS:
At idle, 1000 rpms, 2000, 3000, 4000 and so on, taking out the spark plug to read it after revving the engine 1 minute on each range of RPMS.
Unfortunately i did not have enough budget for a wideband 😄😄

Can you explain your fuel supply setup from tank to carbs? It seems a bit complicated in the bay.

I did also try to use a bike fuel pump, but experimented a lot of issues as i describe it in the attached file.

After a lot of issues, i finally decided to do a simple solution by use a fuel restrictor from the return line to the carbs, without the restrictor the carbs flooded really bad, when the float valves from the carbs are closed the fuel simply retuns to the tank due to the fuel restrictor. I think this configuration could works with the CIS fuel pump as well.

 

[69vdub]

Tried starting mine for the first time a few days ago and couldn’t get it started. Heard a ping sound and quite trying. Noticed the adj cam gear bolts came loose and timing went full advanced. Pulled the head to see if any valves hit and noticed something weird with number 4.

Number 4 plug was black while the other 3 looked new and the area around the valves was black.

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[jinxd12]

@lonchovalle With your carbs at that angle have you or did you run into needle/fuel issues? i know a lot of bike carbs are side draft but those look to be rotated almost 90 degrees out of typical installation. Unless I am wrong. I like the way you have them setup keeping the intake for them off of the firewall!!

 

[Jettaboy1884]

^ I can comment on that. You're correct that bike carbs are essentially a side-draft design. However, if you look at how they are installed on the motorcycle, the sport bike carbs are almost always installed steeper than a 45 degree angle, and often even more extreme at about 60-70 degrees.

Using the float bowl gasket line as a reference point for level goes out the window with a lot of these installations. Here's a couple of motorcycle installs that show the extreme angles:

 

[lonchovalle]

As Jettaboy said, in most cases the carbs in the bikes are installed at about 60-70 degrees, mine are installed at 65 degrees, if reduce this angle the fuel will over filling the bowl, if increase the angle the fuel level will be not enough to feed the jets at high rpms.

As Jettaboy said, the float bowl gasket line is a good reference and must match with the ground level, but depending on the carbs you are using, this angle could be different.

I,ve seen a few configurations with bad angles, causing a lot of issues with the fuel.

 

[YJSAABMAN]

Loving the mounting angle discussion!

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[jinxd12]

Loving the mounting angle discussion!

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Seeing them now not right up against the firewall has changed my opinion on install in 8v JH motors. I may have to try and assemble a parts list!

If a throttle cable linkage design that works with a sweeping motion, and FPR and Return lines ironed out seems like it could be a pretty easy swap without standalone needs on early 80s motors.

 

[lonchovalle]

Seeing them now not right up against the firewall has changed my opinion on install in 8v JH motors. I may have to try and assemble a parts list!

If a throttle cable linkage design that works with a sweeping motion, and FPR and Return lines ironed out seems like it could be a pretty easy swap without standalone needs on early 80s motors.

Pretty easy in fact, once you understand how the carbs works (you must read a bit about it), even with DCOE´s or Dellorto´s, many people fear them but generally because don´t understand how it works.

Recently finished another swap on a Renault R12 of mids 70´s, but the installation is pending.

Some pics: (hope not to enrage the forum because is not a vw 😓)

 

[lonchovalle]

 

[jinxd12]

View attachment 109368 View attachment 109367
View attachment 109369
View attachment 109370

Fab skills on point with those.

Wish I had extra parts and pieces kicking around to give this a go!

 

[jinxd12]

@lonchovalle and @Jettaboy1884 Do you guys know what year R1 carbs are the best/easiest to convert into ITBs? Or just if not R1 carbs then something I can search for to make parts lists to make/order?I see alot of 02-03 carb setups but not many 98-01 setups.

The 02-03 R1 carbs have the orange plugs at every throttle body. Can they be removed and just plugged?

 

[YJSAABMAN]

@lonchovalle and @Jettaboy1884 Do you guys know what year R1 carbs are the best/easiest to convert into ITBs? Or just if not R1 carbs then something I can search for to make parts lists to make/order?I see alot of 02-03 carb setups but not many 98-01 setups.

The 02-03 R1 carbs have the orange plugs at every throttle body. Can they be removed and just plugged?

You're on two different things there. Carbs are carbs and just need a low pressure fuel setup and some jet tuning. The use atmospheric pressure and the vacuum of the engine to inject fuel. ITBs are for fuel injection and have electronic injectors in them and no float bowls or jets. They require other sensors, wiring, and a computer. The carbs are more basic, but probably not as efficient. R1s, and other sport bikes, came with both. Earlier models used the cabs while later models used ITBs and electronic injection. While the 02-03 look a lot more like carbs, the orange plugs are injectors and those models were considered to be fuel injected. Up to 2001 were carbureted and what this thread is dedicated to.

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[lonchovalle]

@jinxd12 i’m not sure yamahas R1’s from 02-03 runs on bike carbs, but i think the Orange plugs you comments are fuel injectors so this are itb’s not carburettors.

im pretty sure all 600 to 1000cc bikes from the 90’s and some models from earlys 2000’s use carburettors, so virtually you can use what it mounts, no matter if they came from yamaha honda kawasaki or suzuki’s.

you can choose it from some of this models:

Yamaha r1-r6
Honda cbr600rr
Honda cbr900rr
Honda cbr1000
Suzuki gsxr600-gsx750
Kawasaki ninja zx1000-zx-7R

please corrects me if im wrong.

 

[jinxd12]

You're on two different things there. Carbs are carbs and just need a low pressure fuel setup and some jet tuning. The use atmospheric pressure and the vacuum of the engine to inject fuel. ITBs are for fuel injection and have electronic injectors in them and no float bowls or jets. They require other sensors, wiring, and a computer. The carbs are more basic, but probably not as efficient. R1s, and other sport bikes, came with both. Earlier models used the cabs while later models used ITBs and electronic injection. While the 02-03 look a lot more like carbs, the orange plugs are injectors and those models were considered to be fuel injected. Up to 2001 were carbureted and what this thread is dedicated to.

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That's exactly what I was asking, but worded it wrong my bad. What years from the R1s or similar are the best to use? I think I was reading in this thread someone was using the R1s from 2001. Maybe I'm wrong.

I guess I didn't understand the reasoning for the orange plugs on the new ones, but now I do, they are for the injectors. Thanks for clearing that up!

 

[lonchovalle]

@jinxd12 What years from the R1s or similar are the best to use?

you can use what you get on hands but by experience i can tell you the carbs must be imaculately clean for an easy setup and sync.
also i suggest to replace of all the gaskets and orings to avoid fuel leakeages.

 

[jinxd12]

@jinxd12 What years from the R1s or similar are the best to use?

you can use what you get on hands but by experience i can tell you the carbs must be imaculately clean for an easy setup and sync.
also i suggest to replace of all the gaskets and orings to avoid fuel leakeages.

That is a no brainer! Always new gaskets, and a full run through in the ultrasonic cleaner! Looking at carbs you have listed above now.