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Discussion Starter #41
Thanks Phil.

Is that standard?

If so looks as if you need to richen the pilots 1 turn out each & drop a size on the mains.

Put the #168 (front) main in the rear & buy a #165 for the front, make sure you get a genuine jet, not an eBay pattern :thumbup:

If you do that I'll bet you will have her reading over 90bhp.
 

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Hi, thinking back it was with the de-baffled stock cans (now sold & back to stock) I have messed with mains/needle & pilots a bit, I think the dyno was with 165 mains fitted, can't recall if it was stock needles or +.5mm shim
I'm not bothered about hp tbh but looking for more punch below 4k.
I reckon the only solution now is dynojet needles. Not sure if I can be bothered anymore though!



However, I do have a theory that the coolant carb heaters heats the fuel at slow/warm running situations leaning low rev response further.


Phil
 

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dont think i can be botherd anymore !! got all the bits to do this and just waiting your final spec on the mod and your backing down !
 

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Discussion Starter #44
dont think i can be botherd anymore !! got all the bits to do this and just waiting your final spec on the mod and your backing down !
Er, backing down?

Read the posts & copy my Dyno run carb setting. It was spot on.

I am sorry if you think we have agreed to some sort of deal here, because we haven't.

This post is only to be used as a guide only.

You might not of noticed :rolleyes: but the project is still on going, I am still fiddling with the fuelling especially with the introduction of the Ducati trumpets.

There is no final, finished setup as of yet & I don't think there never will be, its all a compromise. More torque, power or fuel economy, each one requires different jetting. I just feel there's more to be had by going a little leaner.

At the moment I am reading about CV slide holes & the different characteristics running with 1, 2 or 3 holes make to the throttle response.

BTW Pale tooth, post some pictures of the Ducati trumpets, carb plates, snorkel & pair valve blanking etc.. So we can see your progress....
 

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morning sorry if i cam across as stroppy it wasnt my intention was just a little shocked thats all . the trumpets wont be going on i tried taking them to a local engineering firm to have them turned down to fit inside the vtr trumpets but they couldnt do it and just at the moment i dont have the time doing 12hr shifts at work so ill be using them on my other project which is a supercharged vauxhall victor . the bike goes to a historic formula one engineer to get the carbs and such fitted soon and the exhausted are having a few baffles removed to enhance its presence on the road . it may in the future have a single sided swing arm of a vfr750 ( think thats right the 800's wont fit ) if i can find a wheel that let the bike remain at the same hieght as that was the sole reason i bought it . thanks for the info again sorry if i cam across as stroppy
 

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Discussion Starter #46
sorry if i cam across as stroppy
Me too,

I don't know much about the SSS conversion but I do know the VFR750 swinger won't fit. You need the VFR 800 one :thumbup:

There are a few write ups about the conversion on various Super Hawk & VTR1000 forums if your going to look into it.

Keep us updated if you attempt it :thumbup:
 

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morning just a quick update and a question . ive had the vtr carbs and airbox fitted but not the ducati bell mouths as i was unable to get them turned down to fit a friend who is a mechanic says the bell mouths would have made very little difference anyway ( his point of view not mine and he should know hes a historic f1 mechanic ) ive also had the exhaust repacked and opened up the bike sounds gorgeous now . but it has left me with a slight miss fire any thoughts on what i can do to alleviate this . a rolling road session is planned a little later in the year and possibly a dyno jet kit again i wont be doing the fitting hands are way too big and patience level way too small lol
 

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What revs/load is the misfire?
Vara's seem to be very finnicky with carburation they run (well mine did) very lean at low/mid revs made worse by coolant fed carb heaters (the hotter they run the leaner they get) and very rich at mid/high revs any leaner and it won't run right, any richer & it won't run right...
The only way really is to get it on a dyno & see whats happening.
My general gut feeling is bigger pilot jets, smaller mains AND a different needle profile but you really need to know whats going on first.
On the vtr forum everyone is an armchair expert on jetting so take guidance from there with caution :)
 

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Discussion Starter #49
a friend who is a mechanic says the bell mouths would have made very little difference anyway ( his point of view not mine and he should know hes a historic f1 mechanic )
A Historic F1 mechanic who recons trumpet bell mouths make very little difference.....:rolleyes:

I would ask to see his papers :thumbup:







PS. "The greatest obstacle to discovery is not ignorance, but the illusion of knowledge."
 

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any way a little further info bikes booked in for dyno-jetting and carb balance on monday if funds allow i may even spring for a dyno run see whats at the back wheel now
 

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any way a little further info bikes booked in for dyno-jetting and carb balance on monday if funds allow i may even spring for a dyno run see whats at the back wheel now
Let us know the actual set up & outcome, is it an actual Dynojet kit thats being installed?
I pondered that route but sold the bike first, it'd be good to know if they work :)
 

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Discussion Starter #52 (Edited)
I have also updated the VTR camshaft thread with jetting, I know I have duplicated the thread. But they are reliant on each other :thumbup:

I have been playing with the jetting again after fitting the VTR cams, here are the results.

I did go for an overall leaner setup after the last dyno run results & have been leaning out the mix as it was showing excessive richness across the graph/run.

I felt the jetting was quite close with the current settings, so popped to the rolling road to see what's what.

Here's the setup I used for the dyno run with VTR cams.

Pilot screw
Front------1 3/4 turn out.
Rear-------1 3/4 turns out.

Pilot jets
Front------#48
Rear-------#48

Needles
Dynojet needles fitted (same profile as Std but with the option of different heights).
Front------Clip in 3rd groove from top + 0.7mm washer under clip.
Rear-------Clip in 3rd groove from top + 0.7mm washer under clip..

Mains
Front------#172
Rear-------#175

Slide holes
Std 2 + Dynojet 1
Front-------3 open.
Rear--------3 open.

CV diaphragm springs
Dynojet (short ones)

Air filter
Std paper

Ducati velocity stack mod

VTR cams

TPS
500 ohm's

Porting
Finger porting
.
Intake has been (de flashed) cleaned with 180 grit up to the valve guide & intake rubber trimmed tidily for a seamless transition from carb to head.

This pick shows the increase over the Varadero cams V's VTR cams.



This is the fuelling, the lower two blue lines are the previous (rich) Varadero setup against the (leanish) VTR setup.



Looking at the results of the fuel map the new base line plan is to try this below.

(Richen the top end) Mains back to 175 front, 178 rear.

(Lean the midrange) Lower the needle a clip.

(Richen bottom end) 2 3/4 out on both fuel screws.

Over all, I am quite impressed with the results
 

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Discussion Starter #53
Right, just reset the settings to what was mentioned above.

My theory is that the mains are too lean, so by increasing the mains it will slightly richen the midrange (needle) which is slightly too rich anyway. So I have dropped the needle one groove & kept the washers as is. Then because the pilot was too lean, dropping the needles would make it even leaner so as a ball park setting I have turned them 2 3/4 out.

No doubt I will have to go in again but will see how it responds & report


I have not been for a ride, but will comment that the idle isn't as smooth as when it was prior to the change


Below are some pictures of the needle length comparison, they are only quick picks just to give you an idea


This is the needle height (3rd groove from top) used on the above dyno run
(It was still showing too rich BTW)



This is the new needle height (clip in 2nd groove from top)




Update on the changes.

Been for a little ride & the mains seem good also the needle height, it pulls like a train from 3300rpm.

But under 3000rpm it has a noticeable lean stumble & is popping back through the carb.

Got it home & stripped it again & have screwed both the fuel screws out 3 1/2 turns .

It now needs no choke to start
but once started it idles better, so hopefully It should be a little rich & I will not need to go down the road of purchasing a pair of #50 pilots


Off out for a ride & will update
 

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Discussion Starter #54
Just back from a little ride with the #48's pilots & 3 1/2 turns out & it still has the surging & popping at around 3000rpm.

She does try to clear & sort itself out if I give it a little choke, so I am going to go richer & purchase some #50 pilots.

I think because I have dropped the needles (around 2mm, midrange is the best ever btw) I am out of range using the #48's & the fuel screw.

I have been reading quite a few threads on pilot setup & thought this was an interesting read from Factory Pro.

techjetsused.html, used jets and information


This is the copied link from above



Pilot Jets
The affect of pj size change on idle and cruise operation




Question:Greg Johnson wrote:

> I have installed one of your 1.0 jet kits on my R6 and I am coming to the final parts of tuning it.

> It runs well and passes most of the tests as provided on your tuning guide. It does, however, appear to be lean low down, as there is a "hole" when cracking the throttle wide open at below 2500rpm and at high rpm/part throttle, it shows some surging. I have though set the fuel screws, so that it idles correctly and returns to the correct rpm, when the idle is set below 1000rpm and the throttle is blipped.

> To fix the lean patch, is it better to go the next step up in pilot jets, rather than adjust the fuel screw?

> Will upsizing the pilot jet, require re-adjustment of the fuel screw and thus negating some of or all of the gains made by the larger pilot jet?

> Thanks,

> Greg J


Answer:Greg - Good diagnosis on the pilot jet size -

As far as the pilot... Look at it this way...

There are 4 outlet holes for the pilot mixture. ~3-4 at the butterfly and one "downstream" of that (for 75% of the idle mixture).

1 hole is controlled by the mixture screw and with the other 3 or 4, max flow is limited by the size of the pilot jet.

At idle, 1 hole (metered by the fuel screw) and 1 un metered hole are open.

At cruise, when the "butterfly" is just "cracked", all 3-4 unmetered holes + the 1 metered one are uncovered -

So.....

At cruise, you get those 3 unmetered holes + the metered hole... So, at least 75% of the fuel delivered at cruise is limited by the size of the pilot jet.

At idle, you get 100% of the trimmed 1 hole + a butterfly valve-trimmed amount of the other 3-4 metered holes.

Rule of thumb....
If you go 1 size larger or smaller on the size of the pilot jet, you will change the fuel screw ~1.5x richer or leaner to retain the original idle mixture -

Example:
You have a #40 pilot jet installed (with the proper main, needle height and fuel level already done) and to get best idle, you are 4.0 turns out (from lightly bottomed out).
Cruise seems lean....

So, I'd expect that I could richen the cruise with 1 size larger (42) pilot jet (size of pj is 75% of cruise mixture) and the "trim" the fuel screw "in" for best mixture for best idle (size of pilot is 25% of idle mixture).

To go back to ~ the same idle mixture, after going from 40 pj/4.0x to the 42........ try 2.5x

40 pj / 4.0x = our reference idle mixture
42 pj / 2.5x = ~ same idle mixture
38 pj /5.5x = ~ same idle mixture (this is a "stretch - after 4.5x, not much changes)

(Using another "rule of thumb", if you have the correct pilot jet, the fuel screw will end up at between 1.5x and 3.0x when set for best idle.)

Marc
Update

Had a good talk with a helpful guy at Allens & he talked me into purchasing #50's & #52's


I came off the phone & thought
am I doing buying both sets


Super nice guy, but what a salesman


Still got the feeling not many have tried it on a RRoad running DJ needles this lean (1st or 2nd groove from the top) with the #50's or #52's.

If they have, or know of any rolling road printouts please point them out to me
as I can't find any on the web


It might save me dyno time too
 

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Discussion Starter #56
:thumbup:I would like test it....power supply has to be phenomenal now.:thumbup::thumbup:
It now has more power & torque than many Std VTR's do, so I have exceeded my expectations already.

Since the dyno graph run I've increased the mains & leaned the needles, it now pulls even stronger.

The Top end & mid range really are excellent, so hopefully only the pilot circuit to sort out.

I recon I should see a few more hp on the next dyno run :cool:

I was hoping the new pilots would've arrived today from Allens Performance, so I could crack on. Maybe tomorrow.

Will sort out the pilot situation & update :thumbup:
 

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Discussion Starter #57
The new pilots arrived today so stripped & fitted the #50's, as a random guess I turned both pilot screws out 2 turns.

It started first time with a little choke (which is always a good sign) & it warmed up nice & cleanly as I finished rebuilding it.

There was no stumbling or any blipping needed during this process to clean it's throat or to avoid any stalling.

Once warm it idles at 800rpm smoothly, with no "is it going to stall" thoughts.

Been out for a 50 mile slow country road ride & feel the jetting is really close now, there is still a slight, & I mean slight lean stumble at 2000rpm in top (25-30 mph) going through villages, so I opened the choke very slightly & it went away, so it's still a little lean low down.

When leaving the villages I nailed the throttle to the stop (testing purposes only) the acceleration is faultless & so hard now it really does surprise me.

Going to strip it again now & open the pilots another 1/2 turn to 2 1/2 turns out each.

Just had a look at the #52 pilot in the bag & they sent me a set of #48's in error. quick phone call, no problem sent me out another set straight away & a returns stamp.

Will update with the new pilot setting
 

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Discussion Starter #58
Update on this modification.

All these years hunting for the "perfect" setup has been a waste of time. The carbs I bought from eBay all them years ago were worn out. It has taken a while, but I have managed to get them to work spot on, but the setup will only work with this worn out set of carbs only. So no need to do any of the faf I've been doing with needles etc..

I didn't realise this until recently & It happened by accident tbh, when I was fault finding a misfire. I changed the carbs over to a new set I had on the shelf to see if the fault was fueling. It wasn't but I left them on & later found the issue to be a spark plug :rolleyes:

The jetting in the new carbs was standard (#48 pilots, std needles & trumpets) apart from the main jets which I changed to #178 front & #180 rear.

The performance was excellent, especially the mid range. So I booked it in for a run on the local Dyno.



Green line is Varadero cams with VTR carbs.

Blue line is VTR cams with VTR carbs fitted with Dynojet 185F 190R.

Red line is VTR cams with New VTR carbs fitted with Keihin 178F 180R (ignore the comment on the sheet)

I know its still a little rich in places, but the bike feels flawless.

So to wrap it up, if you are keen to try this mod out. Make sure you get your hands on a low mileage set of carbs :thumbup:
 

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Discussion Starter #59
The difference I've noticed from the rich Dynojet settings to the leaner std jetting is incredible.

On the graph, there's a difference on close to 10bhp in places.

So me being me, I can't resist the temptation to make things better :lol: :rolleyes:

Here's what I've done. I've replaced the Keihin #178Front & #180Rear main jets with Std Keihin #175Front & #178Rear.

I've also removed the oem washers from under the Std needles in an attempt to lean out the midrange a little also.

I also re fitted the Ramair filter I made a few years ago, again to lean it out a bit across the board.

Another thing I noticed is that with me changing the carbs over & also going back to the stock "different height" oem trumpets, there seems to be an improvement to the top end acceleration.

For years I had been using the modified Ducati trumpets that I made. These were of equal length & same height as the taller oem VTR trumpet. They have been excellent for midrange torque & I'd forgotten about the top end rush a shorter trumpet can give.

So I have been fiddling & have made some modified Ducati trumpets the same height as the "different height" oem VTR items. To be fair, I only had to make the short one & use one tall Ducati trumpet I'd previously made.





Here's a picture from a Moriwaki Racing VTR, notice the trumpet heights.

 

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Discussion Starter #60
Quick update, I ran the bike on the dyno again using these slightly leaner settings.

RED LINE

Mains – 175 Front – 178 Rear.

Std needles with Oem washer that sits under the needle removed.

Ducati modded stacks, same heights as the OEM odd items.

Free flow homemade (Ram air foam) filter.

#48 Pilots, 1 ½ out front & 1 ¾ out rear.

STD slide springs & slide holes.

Here’s the run.



I feel that I have learnt something, but it’s been a step backward fitting the modified Ducati stacks, as it’s had the effect of countering the leaner jetting by enriching the afr throughout the range.

I was warned that this would happen over on the vtr1000.org site but I never knew by how much. It seems that by fitting the stacks it’s the same as changing the jet sizes one size richer.

There must be an advantage running large intake trumpets because every race engine runs them.

I would like to run the Oem height modded Ducati stacks again & fit 172Front & 175Rear mains. I wouldn’t be able to lean the midrange using the Oem needles though & would have to fit standard (unfiled) dynojet needles.

I’ve measured the taper of the two needles (Dynojet v’s Std) & the taper is practically the same. The main advantage of running with the dynojet needles is that the groove & clip allows you to richen or lean the midrange.
 
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