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Old 6th June 2010, 18:28   #1
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Default K&N and carb re-jetting for bullet 500 & 350. EDIT: Chart on pg 2

Some performance enhancements for my beast has been in the back of my head for long. Been procrastinating it since i needed it to be in perfect stock condition first and I was searching for some spare parts for long. Anyway I had a complete service done a couple of weeks back with new valves and guides and run in for almost 300 kms and I thought its time i did something.

This weekend seemed to be the prefect time, my girlfriend's having exams on Sunday, so I can not (need not ) spend time with her. None of my friends are around and I have no plans for the weekend... So I woke up saturday morning and was lazily searching for dealers to buy a K&N, that's when I came accross a guy who wanted to sell his RC1060 which has been used for some 4k kms. A couple of calls and I was off to this guy's place. The deal seemed good since a new one costed around 2k and I was not sure if i might revert back to the stock setup, and I was getting this for almost one fourth of the cost.

Bought it home..


Off went my stock air filter and on went the K&N



I checked the jet sizes in my carb. Mine is a VM28 and was running on 27.5 pilot jet and 105 main jet ( yes I am also surprised, it should've been 110 right??? ). Went to JC road, Sandhya spares and bought the below ones.
Main jet : 110, 120
Pilot jet: 27.5 and 30

Could not get any bigger main jet anywhere in JC road, guys if anyone knows where to find some in bangalore, please let me know.

The third part was the free flow exhaust. I had changed the silencer from the long bottle one to the short one recently and the next was the Goldie with removable glass wool (i think its called shakeel's , heard it and I loved the sound). Since that was not readily available, I though that can go in later.

So now it was time to put these to test.
First I wanted to try with just the filter without any mods, and as expected, did not find any change expect for a new extra hissing sound from the filter at all RPMs (like a cobra). I did not quite like it, my stock silencer was VERY SILENT.. But i think I should live with it (Has anyone done anything to circumvent this?)
Attached Thumbnails
K&N and carb re-jetting for bullet 500 & 350. EDIT: Chart on pg 2-img_0157.jpg  

K&N and carb re-jetting for bullet 500 & 350. EDIT: Chart on pg 2-img_0161.jpg  

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Old 6th June 2010, 19:06   #2
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With my limited research about carbs, this is what I understood.

They have 4 different mechanicals to control the air fuel mixture.

0 - 1/8th throttle - Pilot jet and pilot screw
1/8 - 1/4th throttle - The cut-away portion of the throttle valve (Don't know what this or how to adjust this, so left it )
1/4th - 3/4th throttle - The needle jet, controlled by a clip attached to one of the 5 (or 6??) grooves in it.

3/4 - full throttle - Main jet

Now removing the main jet and the pilot jet is simple, you just need to unscrew the float bowl and you can straight away replace them. Getting the needle out and changing is tricky, you need to unscrew the top part..

I, with the help of my mechanic put on the 120 main jet, 27.5 pilot jet and checked the needle position. The needle was a bit bent and got it replaced with another one and the clip position in the middle.
Now to test the various throttle positions, i marked them in my grip using a duct tape. (How else would I find if I am running on 1/2 throttle or 3/4th throttle???)
K&N and carb re-jetting for bullet 500 & 350. EDIT: Chart on pg 2-img_0165.jpg

By this time it was Saturday late night and I was tired. Did a small test ride and the plug seemed OK. I decided to do an extensive test in the airport road on Sunday early morning and retired for the day. Came home, booze and I was asleep before I knew it.

Supposed to wake up at 6.30AM and test my bike, I woke up at 10AM!! Already had a couple of missed calls from my GF and a threatening SMS from her for not wishing her best of luck for her exams.. Cursed myself and hit the road as soon as I could..
I wanted to check the main jet first. But I was too late, the traffic was too much and I somehow managed 3/4 - full throttle sustained for about 10 seconds and then quickly pulled the clutch, cut off the engine and stopped. With the help of a cloth, pulled out the plug and checked - light brown to ash color. Looked good but I am not sure, will check again.
Here are the pics I took (pardon the bad quality, i bought the subject too close to my phone camera and lost focus.. and it was too sunny)
K&N and carb re-jetting for bullet 500 & 350. EDIT: Chart on pg 2-img_0158.jpg
K&N and carb re-jetting for bullet 500 & 350. EDIT: Chart on pg 2-img_0159.jpg
In the meantime, I could not resist clicking one of my beast!!!
K&N and carb re-jetting for bullet 500 & 350. EDIT: Chart on pg 2-img_0160.jpg
By this time I was getting glances from fellow bikers, like someone stuck in the highway with his bike konked up

Now i rode in half throttle for about 1 min again pulled the clutch and killed the engine, and checked the plug. It looks like this..
K&N and carb re-jetting for bullet 500 & 350. EDIT: Chart on pg 2-img_0162.jpg
K&N and carb re-jetting for bullet 500 & 350. EDIT: Chart on pg 2-img_0163.jpg

Looks ok, but towards the leaner side. I think I should lower the clip in the needle to one groove below and check again.

Next in cards is the Goldie, I have to do all these tests again once I put it on.

P.S. All those who's put on the K&N in bullets, how do you protect it from water/rain?? I found it very difficult to wash my bike today evening. Had to cover it with a plastic cover and wash it. Is it ok if it gets wet? What about riding in rains? And how do you protect them from thieves?
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Old 6th June 2010, 19:43   #3
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Hey there mate,

Nice detailed explanation, was a nice read

However, the CI 500 came with 25 pilot & 110 main. It's a good thing that you increased the main size to the stock.

Anyhow, by the pictures posted, your plug looks alright on the mid-range but a little rich on 3/4th to full throttle which is the result of the main jet. I think you should try with 105 once as well. Did you check with a new plug by the way? Also, do you think the atomizer (the area above the main jet, where the fuel mixes with air) has also been changed to something bigger or if the needle you have replaced is a little smaller in diameter than the original?

Take care & ride safe.

And hey, you are one lucky guy to have found the 27.5 pilot, I have been looking all over Delhi but no luck. I although have a collection of main frm 90 to 140.

Regards.
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Old 6th June 2010, 20:10   #4
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Although I bought one 110 main jet, I did not put it in. I went straight from 105 to 120. Do you think the plug shows rich? I thought that was ok.

The pilot jet was stock 25 earlier, I changed it to 27.5. But that would not matter for the mid range right?

I did not change the atomiser and that part looked stock to me. Regarding the needle, when i took it out, i was a bit bent ( could make it out by rotating it).I replaced it with another one from a VM24 lying around in the workshop. Is that shorter in diameter? What difference does it make?

Another peculiar thing I found is that we hardly ride in 3/4 - full throttle even for long rides. Mostly inside city would be 1/4 throttle and occasionally to 1/2 throttle for overtaking.
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Old 6th June 2010, 20:31   #5
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VM 24 needle is shorter, it will be richer, revert back to a VM 28's needle and tune it up. Do it once do it right. Also with just a filter and at Blore altitude 120 is a bit too much for an otherwise stock CI500. Jet down and see the improvement in performance. The pilot you can keep it at 27.5, not a problem, adjust the air screw for an optimum setting, you will get better low end than with 25.
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Old 6th June 2010, 20:52   #6
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Surprisingly when I compared the needles of VM24 and VM28, they were same (atleast in length). So the only difference can be of diameter. Unfortunately I do not have pictures of them. Can I buy just the needle from somewhere?

Regarding the main jet, as I said i could not sustain >3/4 throttle foe long, so I will re-do the test and post the pictures.

Do you feel that the Goldie with glass wool in it would give me the same performance as a FFE ?

I too feel the pilot is the right size.

Last edited by jingaboysr : 6th June 2010 at 20:54.
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Old 6th June 2010, 21:20   #7
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To Protect it from Water\Theft,get a custom cover made for it out of metal.
I got one made for my Bull,from a guy who used to fabricate autorickshaw bodies,an easy job
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Old 6th June 2010, 23:57   #8
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Quote:
Originally Posted by jingaboysr View Post
Surprisingly when I compared the needles of VM24 and VM28, they were same (atleast in length). So the only difference can be of diameter. Unfortunately I do not have pictures of them. Can I buy just the needle from somewhere?

Regarding the main jet, as I said i could not sustain >3/4 throttle foe long, so I will re-do the test and post the pictures.

Do you feel that the Goldie with glass wool in it would give me the same performance as a FFE ?

I too feel the pilot is the right size.
The atomizer/needle jet is larger in diameter in VM28 than VM24 (confirmed from Natco in KB) & as Sankar already said, it is causing the mixture to become a little rich. You can look for the one which is meant for VM28. If you cannot find it there, let me know, I can try looking for it here in Karol Bagh, Delhi.

One quick way of knowing whether or not the main jet is too big, is to suddenly open the throttle while riding. Say for example, you are riding at 45kmph on top gear, & then suddenly you open the throttle to almost WOT for a few seconds. If after doing this, you notice a slight hesitation or sluggishness in the engine it would mean that the main jet is too big causing excess fuel to go into the engine.

Also, with the current setup, there's no harm, but I suggest that you try with a smaller main jet till you can find the needle meant for VM28. Try with 110, I think it should be fine going by the way your plug looks in the pictures.

Lastly, glasswool is an acoustic, thermal & electric insulator & has no relation to the free flow dynamics of an exhaust whatsoever unless, the design constraints the positioning of the glasswool in such a way that it restricts the exhaust gas passage or interferes with it in any way. It is mostly used in silencers to keep the noise levels under limits, & to keep the surface temparature on the lower side. In Bullets, the same silencer would sound something like "pat pat" without glasswool & "dham dham" with glasswool (hope you got the inclination)

Regards.
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Old 9th June 2010, 09:52   #9
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Quote:
Originally Posted by jingaboysr View Post
Surprisingly when I compared the needles of VM24 and VM28, they were same (atleast in length). So the only difference can be of diameter. Unfortunately I do not have pictures of them. Can I buy just the needle from somewhere?

Regarding the main jet, as I said i could not sustain >3/4 throttle foe long, so I will re-do the test and post the pictures.

Do you feel that the Goldie with glass wool in it would give me the same performance as a FFE ?

I too feel the pilot is the right size.
Okay, they might be of almost the same length, but iirc VM28's needle will be slightly longer since the carb is bit taller than 24. Its been a very long time since i last fiddled with them, so don't remember right. Keep the jet needle in centre clip while trying out new main jets, its easier that way.

Try at Sandya Spares, JC Road if you haven't searched there yet. He did have 500 carb parts but that was few years ago.

Regarding Goldie, are you referring to the true Goldie replica aka Shakeel Goldie from Pune, or the Goldie look alike pipe? (Looks almost like Goldie but is a straight taper from the connecting point to the end, Goldie levels out near the end).

And which FFE are you referring to?

A megaphone type pipe without glasswool will be better for performance compared to one filled with glasswool. But difference is only marginal on a stock Bullet engine. I suggest you go with glasswool filled Shakeel Goldie since it gives you better performance compared to stock and won't rupture your eardrums on a long ride, plus its got a sweet note.
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Old 9th June 2010, 11:21   #10
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Quote:
Originally Posted by Sankar View Post
Okay, they might be of almost the same length, but iirc VM28's needle will be slightly longer since the carb is bit taller than 24. Its been a very long time since i last fiddled with them, so don't remember right. Keep the jet needle in centre clip while trying out new main jets, its easier that way.

Try at Sandya Spares, JC Road if you haven't searched there yet. He did have 500 carb parts but that was few years ago.
I actually called up Sandya spares yesterday and they told they have stock for VM28 needles. Could not make it there due to work yesterday, but surely buy it today.

Quote:
Regarding Goldie, are you referring to the true Goldie replica aka Shakeel Goldie from Pune, or the Goldie look alike pipe? (Looks almost like Goldie but is a straight taper from the connecting point to the end, Goldie levels out near the end).

And which FFE are you referring to?

A megaphone type pipe without glasswool will be better for performance compared to one filled with glasswool. But difference is only marginal on a stock Bullet engine. I suggest you go with glasswool filled Shakeel Goldie since it gives you better performance compared to stock and won't rupture your eardrums on a long ride, plus its got a sweet note.
Yes, I was talking about the Shakeel Goldie with the glass wool and the FFE i was talking was the hollow Goldie pipe (the one that tapers all the way till the end and you can see through it). I am also more inclined towards the shakeel one, as it has better base sound. The other one is a torture to ears..

Is the shakeel one available to buy somewhere in Bangalore? Otherwise I have to get it parceled from Pune. :(


Once I get the Goldie and the needle in, i plan to test all the throttle levels once more.

Another peculiar thing i noticed is that my FE has actually increased compared to the stock filter and jets.. I was getting 22-24 earlier, but now in getting 25-26. Am i running lean somewhere?
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Old 9th June 2010, 21:38   #11
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Quote:
Originally Posted by Sankar View Post

A megaphone type pipe without glasswool will be better for performance compared to one filled with glasswool. But difference is only marginal on a stock Bullet engine. I suggest you go with glasswool filled Shakeel Goldie since it gives you better performance compared to stock and won't rupture your eardrums on a long ride, plus its got a sweet note.
Hey Sankar,

Can you please elaborate a bit on this, as to how the glasswool can affect the performance?

Thanks.
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Old 9th June 2010, 22:30   #12
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Quote:
Originally Posted by blackfire_9 View Post
Hey Sankar,

Can you please elaborate a bit on this, as to how the glasswool can affect the performance?

Thanks.
I am assuming since the glasswool would cause some obstruction to the exhaust gases, it cannot be qualified as a fully free flowing exhaust. Hence might decrease performance a little bit.
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Old 10th June 2010, 00:07   #13
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Quote:
Originally Posted by jingaboysr View Post
I am assuming since the glasswool would cause some obstruction to the exhaust gases, it cannot be qualified as a fully free flowing exhaust. Hence might decrease performance a little bit.
Hmm, true & this is what I also mentioned in my previous post, although still wanted to ask Sankar in case there is something that I might not be aware of as yet & could know about.

My views:

As for your bike getting a higher gas mileage, it depends on a number of factors actually. It's debatable, although it certainly is possible with a free flow setup ( intake & exhaust ) & this means more air into & out of the engine as quickly as possible. With only an intake, you are only helping a very small increase in the quantity of air & not the 'quickly' part.

One thing that happens is that the fuel burns cleaner & the combustion is more complete (due to the slightly more oxygen available now).
At the same time, more air necessitates more fuel but this does not depend alone on the free flow nature of the intake (more volume of air) nor simply on increasing the size of the jets. The velocity of the air with which it flows into the venturi is important & maybe that has dropped could be any reason like a leak, or a larger than required diameter of the intake assembly etc) in your case resulting in lesser fuel being actually atomized with the intake air leading to a better fuel efficiency.

OR,

Another point to consider & ponder is the condition of your stock filter prior to installing K&N. Was it dirty or clogged & had it been long since you had changed it last? Also did you wash your carb, jets or other related parts in this chain before installing this new setup? If yes to above questions, then the clogging & dirt in this chain would have lead to lower air (volume of air) & ultimately a lower velocity & a lower than normal gas mileage. In fact, K&N's claims (of improved mileage) are based on certain things, one of which quotes them saying that their filters stay cleaner longer.

OR,

The filter is actually smaller for the 500cc, although free flow but smaller for this big an engine & so it is probably not able to supply this requisite amount of intake charge to the engine.

I feel it could be either of the first two cases as above or both playing some role to an extent, however do check up for the third point as well.

Also when you put in a free flow exhaust, it not only reduces the backpressure but also reduces the pumping losses that the engine has to suffer in case of a restrictive exhaust, so you would most probably get a better gas mileage with a free flow exhaust provided the other factors are kept constant.

Your are not running lean looking at the pics of your spark plugs. Maybe you can do a plug chop with a new plug as suggested before to be more sure.

Thanks.

Last edited by blackfire_9 : 10th June 2010 at 00:15.
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Old 10th June 2010, 12:15   #14
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friends,

I like to do few modifications. Let me know if possible and your valuable thoughts are welcome.

1. Rear Tyre: I would like to go for a wider Tyre - like the one in Classic 500. What do you suggest? Should I change the RIM?

2. Silencer - Want to change it to bend silencer as in Classic 500

3. K&N filters - is is available in the market?

4. Iridium Spark plugs - I couldn't find it in Coimbatore. Any advice?

Thank you,
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Old 10th June 2010, 12:41   #15
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Quote:
Originally Posted by blackfire_9 View Post
Hey Sankar,

Can you please elaborate a bit on this, as to how the glasswool can affect the performance?

Thanks.
Quote:
Originally Posted by jingaboysr View Post
I am assuming since the glasswool would cause some obstruction to the exhaust gases, it cannot be qualified as a fully free flowing exhaust. Hence might decrease performance a little bit.
A megaphone pipe uses exhaust pulse generated (wave) to do scavenging of the gases, and in engines with valve overlap (iirc iron engine bullet with stock cam has nil of it, exhaust opens after intake is closed) a properly designed megaphone pipe (or exhaust header in case of multicylinder) will help sucking in fresh mixture through the inlet valve during the period of valve overlap.

When glass wool is filled pulse/wave theory goes out of whack, and it ceases to be a megaphone, but just a straight through muffler with glasspack.

What i have given is just a very brief description. There's more to it.
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