loud big bore kit?

[def215]

hello,

so i recently bought a china scoot off of amazon. so far ive only put about 150Km on it and ive decided to start modding it. ive installed a 47mm big bore kit on it this weekend and it definitely has more get up and go. but im hearing sounds that ive never heard before i installed the big bore kit, like a ticking. its around the fan cover area. it seems to happen when the engine is warm and ive ridden a few miles to get it to operating temps. on a cold start i dont hear the noise. 

here is a video of the sound:



i have a bit of paranoia with unfamiliar sounds coming from an engine with past experiences lol. im not sure if its normal or not. 

i havent changed the oil yet, so that should be something i do soon, gonna go with a 15w-40 truck oil.


it looks like timing is good, the T mark is lined up on the flywheel and the cam was set to the big hole perpendicular to the head with the small holes parallel to it. the head bolt/nuts are torqued to 15lb/ft as specified. the valve lash also looked good. i had the feeler gauge in there and it lookslike lash is set to .002 for both intake and exhaust(i need to get myself a 9mm wrench to set valvelash ) 

on top of the big bore kit, it also has an exhaust as well as a blue racing CDI in it. im running 89 octane(US) at the moment.

im not sure if its just me that is paranoid about these sounds or if its an actual issue. i did read that the big bores are louder, but that was one thread i read, and i cant seem to find it anymore. it appears to run great though, it has more torque and has a greater top speed now. 41 mph with all mods opposed to 35-36 all stock.

thanks for all of the help on this forum so far! 

[GrumpyUnk]

Sounded like valve lash to me. I suggest getting a 9mm or a small adjustable wrench. One is available that is about 4-5" in length that should do the job. It doesn't sound bad, just a bit tappy.
Is the .002 in English or metric?
tom

[claydoh]

Your engine may like a slightly different valve lash from stock, especially with new parts. It may take some trial and error.
My current ride likes .0025 inches (.06mm) intakes and somewhere between .003 and .004 inch (.08mm) on the exhaust, else it makes similar ticks. My manual specifies .03mm to .05mm which seems too tight, but I have a BBK/head/camshaft on it anyway.

Other resources seem to agree on the .003inch to .004ish inch range, or even .002 to .005inches. Clear as mud

[FrankenMech]

I have always used .004" on air-cooled engines. I would rather have a little noise rather than burned valves and constant maintenance woes just for some imaginary performance gain.

[GrumpyUnk]

The combination of aluminum head and a cast iron cylinder make figuring the 'hot' vs 'cold' clearance a task. It seems that the clearance on at least some increases due to the differing expansion rates of Fe vs Al. I have two machines, a 129QMB and a CG250 that seem to get a bit louder when they are at operating temperature. I think as heat causes the cylinder head to expand, it moves the cam followers or rocker arms away from the valve stems, increasing clearance.
It is either that, or the heat is reeeaaallly thinning out the oil and allowing a lot of clatter.
Bet there could be arguments for days about the proper settings. I don't mind, actually enjoy, a bit of valve noise, but too much tappy can cause more wear on the rocker arm tips where they impact the stem.
Adjusted the valves on a Renault Alliance one time. I spent the time to insure the adjustment was very close to spec. Sat on top of the engine as I recall. When done, it sure sounded nice, and ran very well. I think it was 1400cc in displacement, but would comfortably cruise all day at 70mph.(110-120kph) And still get good gas mileage. Too bad the quality of the rest of the car was so lacking.
tom

[def215]

i realized there were replies to the thread, but thanks for the reply guys!

i did end up getting a 9mm wrench and a feeler gauge and re-did the valve lash. i did try anywhere from .003-.004 on intake and .004 to .005 on the exhaust and i still do hear the tick, im just accepting the fact that there will be noise coming from it. i settled with like a .0035 on the intake and .0045 on the exhaust. i felt that would be good. im just probably being a bit paranoid to be honest in my original post.

but thanks for the feedback guys!

[GrumpyUnk]

Well, sometimes they ARE chasing you. ... Better to pay attention to the valve lash and have the engine work than to ignore it and have the engine become difficult to start, run poorly, and have less power. Do it long enough(ignore) and you can satisfy your curiosity about valves when you replace the burnt ones or install a new cylinder head. The valves transfer heat to the cylinder head each time they close. May not be for a long period of time, but apparently it is enough in most cases. Keep them too tight, and they won't kiss the valve seats as amorously and will get overheated, which can lead to poor sealing.
tom

[def215]

im realizing these need a bit more attention to what im used to, since im more accustomed to small 2-stroke engines(i.e. gopeds and motorized bikes).

i know it will need more maintenance than im used to and i gotta keep on it. it only has 460KM on it so far, im not even sure if i hit any maintenance interval for it yet. but i feel like i tinkered more than i rode the thing

[scooter7878]

I get that same noise I'm thinking the thinning oil theory. I'll be honest it kinda drives me crazy but I've tried all different valve clearance and some different oils to no aid I've just learned to live with it I've got about 5000 on my kit and it's been doing it the whole time with no issues so

[scooter7878]

May 17, 2021 11:44:06 GMT -5 def215 said:

hello,

so i recently bought a china scoot off of amazon. so far ive only put about 150Km on it and ive decided to start modding it. ive installed a 47mm big bore kit on it this weekend and it definitely has more get up and go. but im hearing sounds that ive never heard before i installed the big bore kit, like a ticking. its around the fan cover area. it seems to happen when the engine is warm and ive ridden a few miles to get it to operating temps. on a cold start i dont hear the noise. 

here is a video of the sound:



i have a bit of paranoia with unfamiliar sounds coming from an engine with past experiences lol. im not sure if its normal or not. 

i havent changed the oil yet, so that should be something i do soon, gonna go with a 15w-40 truck oil.


it looks like timing is good, the T mark is lined up on the flywheel and the cam was set to the big hole perpendicular to the head with the small holes parallel to it. the head bolt/nuts are torqued to 15lb/ft as specified. the valve lash also looked good. i had the feeler gauge in there and it lookslike lash is set to .002 for both intake and exhaust(i need to get myself a 9mm wrench to set valvelash ) 

on top of the big bore kit, it also has an exhaust as well as a blue racing CDI in it. im running 89 octane(US) at the moment.

im not sure if its just me that is paranoid about these sounds or if its an actual issue. i did read that the big bores are louder, but that was one thread i read, and i cant seem to find it anymore. it appears to run great though, it has more torque and has a greater top speed now. 41 mph with all mods opposed to 35-36 all stock.

thanks for all of the help on this forum so far! 

. I use Castrol 20w 50 4t synthetic oil it seems to be most quite with this oil and I got over 5000 on a Amazon cylinder kit and I beat the crap out of my scooter I regularly hitting 9800 rpm I'm full throttle 95 percent of the time so I can attest the oil works good lol

[GrumpyUnk]

It seems the popular oils to use are the diesel rated lubes, 15W-40 being the most mentioned. The cam followers are not roller tipped, and thus need the ZDDP that was removed from spark ignition oils. Delvac, Rotella, RPM Delo and even Wally's Super Tech are all usable and will do a decent job. Just change regularly, using both drains to insure as much as possible is replaced. Check the level regularly.
tom

[kevino]

I know little about scooters.   I know more about air-cooled VWs.  I know if there's not enough valve lash the engine burns up.  If there's too much the valves are noisy but the engine runs cool.   I had a '67 VW bug that make noise in one cylinder.  I played with the valves but it didn't help.  Eventually figured out there was a gap where the head met the cylinder.   I put in a new cylinder which solved the problem.