[rahul4321]

Can anyone help me with a weird sound on my UCE 350 Electra? The sound only comes up in one particular instance. When i go down a steep ramp/slope and i ride over the exact point where the slope ends and a horizontal road in front begins (where the front suspension compresses), i hear a distinct 'buduk buduk" sound from somewhere in the front. The problem wasn't there before i had an oil leak in my front suspension and it had to be opened up to replace the oil seal. Any ideas on what it can be?

[ArizonaJim]

dkaile: I haven't had access to the carburetor used on the Himalayan so I will have to answer your question as if it were the regular, run of the mill carburetors.

The mixture screw you see adjusts the idle mixture only. It has little if any effect on the fuel/air mixture when the engine is running at higher speeds.

To adjust the fuel/air mixture at higher engine speeds, the main and pilot jets require changing to a different size. If the carburetor has a throttle slide needle, it may require readjusting or even changing, depending on the jet combination.

This is not IMO, a job for a layman. The number of combinations of different jets and needle adjustments is almost endless and should only be done by someone who is totally familiar with the particular engine, carburetor requirements needed for the specific altitude.


As the Himalayan is a brand new motorcycle, I doubt that anyone outside of Royal Enfield has the slightest idea of what the correct jetting is for any given altitude.

During testing, I'm sure RE collected volumes of information about the needs of the engine at any altitude.
Your Royal Enfield dealer/mechanic should have access to factory data for the proper jets for the altitude you want to ride at. They also should have access to the correct jets for that particular carburetor.

I will mention that it is better for the engine if it is running rich than it is for the engine to run lean.
___________________________

surjaonwheelz:
Assuming the plastic bushings were installed correctly, they should not need lubrication as the material they are made from provides it. If you want to spray WD-40 or other lubricants into the area where the bushings are, it own't damage anything but it will serve as a dust collector and the dust, over a long period of time can cause wear.

Before trying to lubricate the bushings, set the motorcycle on the side stand.
Then, loosen (but do not remove) both the upper and lower nuts that hold the spring/shock absorbers in place.
The nuts should be loose enough to allow the eyelets to rotate but not to slide sideways.

Once done, get on the motorcycle and make it move up and down by applying your weight to the seat. Do this a few times and then return the motorcycle to rest on the sidestand.

Now, fully re-tighten the nuts and try the load test again.
I may be wrong but I think your squeak will be gone. Let us know.
_________________

rahul4321:
When you had your seal(s) replaced, they had to remove the front fork tubes.
It is possible that when they removed or reinstalled them the bearings in the steering head became loose. This would allow the entire front fork to move when the bump was encountered.

Return the motorcycle to whoever did the seal replacement and suggest that they check the steering head bearing adjustment.

If you want to do this yourself and you have the proper tools, place the motorcycle on the center stand.
Then, loosen the bolts that clamp the fork tubes on the lower arm bracket of the steering head. There is one on each side.
They should be loose but not removed.

Raise the front of the motorcycle by placing a screw type jack under the front engine mount.

With the front of the motorcycle jacked up to get the front wheel just off of the tarmac, unscrew the large chrome nut that provides load to the steering stem. It is right in the middle, below your handlebars. It should only be slightly loosened, not unscrewed or removed.

Now, tighten the nut using a large wrench. It should be fairly tight.
Again, back off the large nut, just to the point that it is loose and turns with finger pressure. Then, once again tighten the large nut to 2-4 NM (2 lb/ft) of torque.
This is a very light torque but it is all that is needed to keep the ball bearings in the upper and lower end of the steering stem snug.

Don't forget to re-tighten the fork tube clamp bolts on the lower steering bracket.

(Don't be tempted to just loosen the steering head nut and then tighten it up to 3NM. You must loosen the lower clamp bolts so the fork tubes can slide upwards as the big nut is tightened the first time to the heavy torque.)

[kaustubh_vaze]

Hi folks,
Been a long time since I have posted on TBHP.
I will first mention an experiment that I tried on the AVL 350 TB that I have -
I bumped up the compression by about 1 (faced the head around 0.8 mm). Then made the famous Somender Singh grooves. See the picture for details.
Reassembled the head.
Bike runs like a dream. Improved bottom end and good pull in all gears.

Now the problem - Recently noticed that bike is emitting black smoke only at idle. When revved/revved hard, the smoke goes away.

Is it an issue with carb idle setting or tappets?
Cannot find the root cause as yet.

Anybody faced such a problem especially after facing the head?


Regards,
Kaustubh

[ArizonaJim]

Black smoke is almost always a sign of the air/fuel mixture being too rich.

Several things can cause this overly rich mixture, among them, a dirty air filter, the choke or enrichment device failing to open or return to an inactive condition or, the float is allowing too much fuel into the float chamber.

As your engine quits making the black smoke when it is revved I will rule out the dirty air filter and choke/enrichment system.

That leaves the idle mixture screw as the most likely culprit.

Not knowing the exact carburetor you have installed I will mention that on some types, the screw controls the amount of fuel that is being allowed into the engine.
With this style, screwing it in (clockwise) reduces the fuel and makes the mixture leaner.
Likewise, unscrewing it counterclockwise it will allow more fuel into the engine making it richer.

Other carburetors are just the opposite.
Their mixture adjusting screw controls the air supply that is allowed thru the idle circuit.
With this design, unscrewing the screw counterclockwise allows more air into the circuit making the air/fuel ratio leaner and screwing it in clockwise reduces the amount of air into the circuit making it richer.

Most carburetors are the former type so try screwing the adjustment screw in.

If this is correct for your carburetor, the engine speed should increase and the black smoke will decrease.

When turning the screw in further makes the engine start to misfire and slow down, unscrew the screw about 1/4 to 1/2 of a turn and your problem should be gone.
If this doesn't fix it, read on.

Occasionally, the float will develop a internal leak. This will cause the float to sink a bit, allowing more fuel into the float chamber.

As the fuel level in the chamber rises, the air/fuel mixture will become richer.
While this effects the engine at all speeds including WOT, it is most evident at an idle speed.

If the engine has been ridden at high speeds for some distance and on shutting the engine off, the spark plug is checked, it will have evidence of carbon buildup on the center electrode.
If this is noted, suspect the float as the culprit.
I should mention that occasionally, the float chamber shut off valve that the float controls will become loose. This will allow fuel to bypass the valve making the engine run rich.

This leaky valve problem often only shows up when the engine is idling because the small amount of fuel that is bypassing the valve will overfill the float chamber as the engine idles, but when the engine is run at a higher speed, the higher fuel consumption will burn off the excess fuel making everything seem normal.

If you take the float chamber bowl off of the carburetor, tighten the float valve snugly to prevent leaks of this kind.

[surjaonwheelz]

Originally Posted by ArizonaJim

surjaonwheelz:
Assuming the plastic bushings were installed correctly, they should not need lubrication as the material they are made from provides it. If you want to spray WD-40 or other lubricants into the area where the bushings are, it own't damage anything but it will serve as a dust collector and the dust, over a long period of time can cause wear.

Before trying to lubricate the bushings, set the motorcycle on the side stand.
Then, loosen (but do not remove) both the upper and lower nuts that hold the spring/shock absorbers in place.
The nuts should be loose enough to allow the eyelets to rotate but not to slide sideways.

Once done, get on the motorcycle and make it move up and down by applying your weight to the seat. Do this a few times and then return the motorcycle to rest on the sidestand.

Now, fully re-tighten the nuts and try the load test again.
I may be wrong but I think your squeak will be gone. Let us know.

Jim,
I tried your tip, but was not successful. Loosening the shock absorbers didn't reduce the noise.
When the swing arm was loosened, the noise was gone hence confirming the origin. Going for short term benefits I lubricated it, tightened it and the noise is gone.

Thanks!

[TheRajput]

My six months old CL350 has completed 2600 kms and the stock exhaust has been replaced with a wild boar. This is the first rainy season with the bike and yesterday while riding in heavy rains the engine died thrice within 10 kms of riding, and the engine would fire only after 8-10 kick starts. What could be the reason for this?

[KkVaidya]

Originally Posted by ArizonaJim

I should mention that occasionally, the float chamber shut off valve that the float controls will become loose. This will allow fuel to bypass the valve making the engine run rich.

This leaky valve problem often only shows up when the engine is idling because the small amount of fuel that is bypassing the valve will overfill the float chamber as the engine idles, but when the engine is run at a higher speed, the higher fuel consumption will burn off the excess fuel making everything seem normal.

Dear Arizona Jim: Have always found your posts to be technically sound and easy to understand. Thank you for all the contribution we get from you.
I would like to know what is the reason for smell of petrol, kind of un-burnt, that also gives a slight burning sensation to eyes in a closed area? Is it an indication of a rich mixture even if there is no visible smoke from the exhaust? I have checked for any external leakages and found none ; although a leaking petrol has a different smell.

[The Great]

Originally Posted by TheRajput

My six months old CL350 has completed 2600 kms and the stock exhaust has been replaced with a wild boar. This is the first rainy season with the bike and yesterday while riding in heavy rains the engine died thrice within 10 kms of riding, and the engine would fire only after 8-10 kick starts. What could be the reason for this?

This is clearly indicating at water seepage inside your petrol tank. Follow the instructions ArizonaJim gave in the previous comments.

[thirst4torque]

Raising this query on behalf of a friend who is not a T-BHP member.

Can anyone tell me what is the exhaust gas temperature and pressure at different RPMs at exhaust manifold of a RE engine (preferably for 500cc engine). It is for an educational project.

[ArizonaJim]

Originally Posted by TheRajput

My six months old CL350 has completed 2600 kms and the stock exhaust has been replaced with a wild boar. This is the first rainy season with the bike and yesterday while riding in heavy rains the engine died thrice within 10 kms of riding, and the engine would fire only after 8-10 kick starts. What could be the reason for this?

A sudden appearance of an engine misfireing during rains usually indicates a loss of spark at the spark plug.
In most cases, this is due to water seeping into the joint between the high voltage spark plug wire and the ignition coil or the spark plug cap.
While the joint may be totally adequate at preventing an escape of the high voltage when it is dry, water acts as a conductor which can short out the wire.
Check the wire connections at both ends to make sure it is tightly installed. Also, wiping off any dirt or grime that has covered the wire will help to eliminate the problem.
While your checking the wire, also make sure the spark plug cap is fully seated on the spark plug.
The spark plug cap (connector) has a rubber seal at the bottom (mouth) to prevent water from entering. This seal only works when the cap is fully seated. Applying a coating of di-electric grease to the spark plug insulator can also help this joint seal against water.

Originally Posted by KkVaidya

Dear Arizona Jim: Have always found your posts to be technically sound and easy to understand. Thank you for all the contribution we get from you.
I would like to know what is the reason for smell of petrol, kind of un-burnt, that also gives a slight burning sensation to eyes in a closed area? Is it an indication of a rich mixture even if there is no visible smoke from the exhaust? I have checked for any external leakages and found none ; although a leaking petrol has a different smell.

The smell is due to a slightly rich air/fuel mixture.
Petrol engines runs best at idle speeds with a slightly rich mixture so one could consider it to be normal unless black smoke is being emitted from the exhaust pipe.
Although modern vehicles have design features to reduce emissions, they aren't perfect and often, people will disconnect or remove them under the (usually false) idea that doing this will increase performance.
It rarely accomplishes the increased power/fuel economy goals but it always increases the amount of hydrocarbon emissions (like the smell of raw fuel in the exhaust).
I'm not suggesting that you frinkled with the emission devices or that anything is really wrong with your motorcycle. I'm just saying some people do.
If your engine is running fine, don't worry about it.

By the way, if you notice this smell it indicates the engine is producing carbon monoxide, a deadly gas that can easily kill you if your in an area with poor ventilation. NEVER run a petrol engine in an enclosed room.

Originally Posted by thirst4torque

Raising this query on behalf of a friend who is not a T-BHP member.

Can anyone tell me what is the exhaust gas temperature and pressure at different RPMs at exhaust manifold of a RE engine (preferably for 500cc engine). It is for an educational project.

The question is too broad to answer with any real values because the exhaust temperature is totally dependent on how much power the engine is producing and what speed it is running. As these are constantly changing I can't give a good answer.

I can say that when the engine is just idling, the temperature will be roughly in the 170° C-260° C (350° F-500° F) range.

At wide open (full) throttle and high engine speeds the exhaust temperature will be over 870° C(1600° F) at the exhaust valve.

In all cases, the exhaust pressure will depend on the size and length of the exhaust pipe (in addition to the throttle setting and engine speed).

Although larger in diameter and shorter in length reduces the exhaust pressure, this is not always good for producing large amounts of power.
(Many think it is.)
In fact, decreasing the exhaust pressure can have a negative effect.

This enters a very complex subject area iand in this limited space I cannot get too far into it but I will touch on a few things.

A small diameter exhaust pipe will create higher pressures but at the same time, it will increase the velocity of the gas in the pipe.
High speed gas has more energy than low speed gas.

The gas being ejected into the pipe is in pulses as the exhaust valve opens and closes, and it is this that makes the thump at idle or the ROAR at Wide Open Throttle (WOT) conditions. Obviously, at WOT conditions there is a lot of energy present that could be put to work.

It's an interesting fact that as these positive pressure pulses travel down the pipe and reach the end, they create a negative pressure pulse that travels back up the pipe to the exhaust valve.

Because of the way camshafts work, towards the end of the exhaust stroke, while the exhaust valve is closing, the intake valve is opening. In other words, there is a short period of time when both valves are open.

Now, if we time that negative pressure pulse just right by using a exhaust pipe of the right length, the negative pulse will enter the still open exhaust valve and not only pull the last bits of exhaust from the cylinder but it will also pull some new, fresh charge of air/fuel into the cylinder thru the intake valve.
This in effect, supercharges the engine and can result in a noticeable increase in engine power.

This works in both 2 and 4 cycle engines and riders of high performance 2 stroke bikes are well aware of this when the engine "comes on the pipe".
I've ridden both 2 and 4 cycle motorcycles with "tuned exhaust pipe(s)" and can say, at lower engine speeds, opening the throttle to WOT the engine starts to pull strongly.
As the engine speed increases, suddenly, the negative exhaust pulses start to reach the exhaust valve or port at the correct time and pull in the extra air/fuel and the power increases to the point that the handlebars try to pull out of my grasp and the seat pushes on my rear as the front wheel goes into the air.

It is definitely a Power Rush, one hard to forget.

My apologies to our members if I got carried away with this answer.

Now, back to the regularly scheduled questions about Royal Enfields.

[TheRajput]

Is it recommended to apply antirust solution (the copper colour) over chrome parts on the bike during rains? Will it have any corrosive effect over the metal?

[Devrishi]

Hi... i am in market to purchase tube for my Desert Storm stock front tyre size 90 / 90 -19, the MRF tubes available are 3.00 x 19 & 3.25 x 19.

Kindly suggest which tube size to pick up.

Thanks

[navin_v8]

Originally Posted by TheRajput

Is it recommended to apply antirust solution (the copper colour) over chrome parts on the bike during rains? Will it have any corrosive effect over the metal?

Mate to be frank some do it and some don't. I have been applying the anti rust coat on all my RE's since I have owned them and have been somewhat satisfied with it. If you wish to get an antirust coat done then do bear in mind that it is NOT supposed to be applied on aluminium parts and plastic chrome. Removing the antirust coat is a tough job but can be removed in a jiffy using petrol soaked rug.

Originally Posted by Devrishi

Hi... i am in market to purchase tube for my Desert Storm stock front tyre size 90 / 90 -19, the MRF tubes available are 3.00 x 19 & 3.25 x 19.

Kindly suggest which tube size to pick up.

Mate I believe all the new UCE's except Electra and Standard 350 uses 90/90 tyre size. It is better to stick to the same size tube which came as OEM. I would never compromise with tyre specs as it compromises safety.

Originally Posted by navin_v8

Mate I believe all the new UCE's except Electra and Standard 350 uses 90/90 tyre size. It is better to stick to the same size tube which came as OEM. I would never compromise with tyre specs as it compromises safety.

I came across this website which shows tyre size conversion chart and as per the chart you can either opt for 3.00 or 3.25 in 19 inch size for a 90/90 19 inch tyre profile.

Mods sorry for back to back posts. Kindly merge.

[TheRajput]

Originally Posted by navin_v8

Mate to be frank some do it and some don't. I have been applying the anti rust coat on all my RE's since I have owned them and have been somewhat satisfied with it. If you wish to get an antirust coat done then do bear in mind that it is NOT supposed to be applied on aluminium parts and plastic chrome. Removing the antirust coat is a tough job but can be removed in a jiffy using petrol soaked rug.

Today I inspected my bike closely and noticed a small amount of rusting on the silencer and the crash guard. So I think it would be a good decision to coat the chrome parts with the anti rust solution. BTW, is there any specific brand of antirust solution which is to be used?

[bullet_chacha]

I ride a 2015 standard 500 with almost 10k on the odo. The previous ride was the C500 which was traded off with 55 odd kays on the odo. Although I'm in love with the STD 500, but somehow feel the lack of power delivery despite plonking a K&N and a tune up accordingly with combination to a free flow megafone.

Offlate I've been contemplating upon some performance mods including an upjet and a bigger card. Tried looking around the Internet, but could hardly find any info.

Can someone please throw some light over it and let me know what carb or jets to replace? Will shaving the head help too?

Pic of my bike attached.