pewpew
Scoot Enthusiast
Posts: 254
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Post by pewpew on Jan 5, 2020 22:22:30 GMT -5
Hello! Sorry for my bad english/writing skills in advance.
So i built this Yamaha aerox engine a few months back, specs:
Stage6 70cc Racing MK2 Doppler 12mm crank Stage6 bearings and seals Yasuni C21 exhaust Stage6 intake kit with stage6 viton reeds Stage6 mk2 24mm pwk carb (38 pilot/122 main/needle position second from top) Stage6 air filter Stage6 variator (5.2g rollers) Stage6 pulley Stage6 belt Stage6 clutch bell Malossi fly clutch (yellow malossi springs) Stock rear pulley&gearing. (Red malossi torque spring)
It worked well in the beginning, had tons of power and did 114.2KM/H or 70MPH, then started all the problems, it crackles and bogs down on moist weather or winter conditions, but works fine on dry weather. Maybe the ignition wiring? Then came more problems, it started losing power and the reeds exploded (bent into the reed cage) (pressure back to reeds??) replaced with the same new reeds, at the same time with the first reeds, it started to launch from high gear and didnt have much power.
Same thing happened week later (reeds exploded into the reed cage), took the engine apart and the piston was soft seized. Also at the same time as the second reeds exploded, i changed the torque spring to +106 blue malossi spring, it had tons of power and launched almost perfectly. But at like 80km/h everything in the variator started to slip (belt left marks on the front pulley and variator, and the clutch was glossy) Nothing helped, tried to change the rollers to much heavier, different belts and different clutch bell. I dont know what caused these but i ordered a ton of parts like: Torque control clutch, +61% torque spring, Vforce3 reeds and tons more. I need to know what can cause these so i dont ruin the new parts as soon as i get them installed. I am gonna try to put some videos in the post if i can.
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Post by Zino on Jan 5, 2020 23:07:23 GMT -5
Winter to dry what temps difference are you talking ?
Focusing on the engine first
Could you be jetted perfect for summer but be lean for winter ? What is your Squish set at ? What is your compression ratio ? Could you have ran some lower octane fuel through it causing detonation ?
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Post by ryan_ott on Jan 5, 2020 23:14:09 GMT -5
I’m thinking the reed failures are being caused by backfires damaging the reeds and they eventually fail. I had it happen. Check over the ignition wiring, replace the plug, check or replace the wire and boot, a failing CDI could cause improper timing.. do you have another you could use for testing, borrow from a friend.
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Post by benji on Jan 6, 2020 0:27:57 GMT -5
specs:
Stage6 bearings and seals Stage6 intake kit with stage6 viton reeds Stage6 mk2 24mm pwk carb (38 pilot/122 main/needle position second from top) Stage6 air filter it crackles and bogs down on moist weather or winter conditions, but works fine on dry weather. Maybe the ignition wiring?
maybe the ignition, but im leaning towards an airleak causing a lean condition during moist/cold weather (which would displace fuel in the mix i think). These are going to be your problem components in my opinion. I've had a stage6 carb, and it leaked air. I've had others tell me their stage6 carbs leaked also. The intake being from stage6 is suspect on that fact alone, I've been burnt by stage6 parts before and have a low opinion of them. The vforce reeds should work better, I would also try doing an airleak test. I bet you find that intake is leaky.
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Post by benji on Jan 6, 2020 0:30:52 GMT -5
a failing CDI could cause improper timing.. do you have another you could use for testing, borrow from a friend. this is probable also. I had a cdi that would act up in wet weather, it was going bad.
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pewpew
Scoot Enthusiast
Posts: 254
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Post by pewpew on Jan 6, 2020 12:39:50 GMT -5
Winter to dry what temps difference are you talking ? Focusing on the engine first Could you be jetted perfect for summer but be lean for winter ? What is your Squish set at ? What is your compression ratio ? Could you have ran some lower octane fuel through it causing detonation ? In winter and dry weather there is no water on the ground or raining so it works fine. The temps differ alot in here, sometimes its +10 Celsius and sometimes -10 Celsius. I put 122 main jet instead of 118 that worked fine in the autumn. Im gonna put the carb settings to alot richer and try to set it from there. My squish is set at 0,7mm. Im not sure about the compression ratio, i run 98 octane fuel.
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pewpew
Scoot Enthusiast
Posts: 254
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Post by pewpew on Jan 6, 2020 12:42:20 GMT -5
I will try new ignition parts and try to seal the wires. Can i check for leaks by starting the engine and spraying soapy water?
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Post by 90GTVert on Jan 6, 2020 17:10:16 GMT -5
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pewpew
Scoot Enthusiast
Posts: 254
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Post by pewpew on Jan 6, 2020 21:53:30 GMT -5
i dont know any stores here in finland to get those things for the pressure test
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Post by Zino on Jan 6, 2020 22:33:38 GMT -5
A unlit propane torch with gas along the seams of the carb head gasket and base gasket works okay . With the scooter running you will hear a change in the idle.
A leakdown tester is better Get creative lots of videos on youtube with other styles to make I rigged one up with a a bike pump and a up to 10 psi gauge some tubing and a wine stopper I drilled out .
I have used soapy water to check for a exhaust leak but a quicker way is by taking a gloved hand when the scooter is running and plug the exhaust with a wet rag if it kills quick your exhaust is not leaking if it keeps running you have a leak.
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pewpew
Scoot Enthusiast
Posts: 254
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Post by pewpew on Mar 27, 2020 22:00:48 GMT -5
And the problems continue... My current setup is: -Stage6 Mk2 racing cylinderkit -Yasuni c21 exhaust -Mvt Premium ignition (2,5mm btdc) -Stage6 Vforce3 reeds -Stage6 intake kit -Stage6 Mk2 24 pwk carb (42 idle, 135 main needle 1 below bottom) -Stage6 air filter -Stage6 subframe -Malossi MHR overrange variatorkit -Stage6 torque control mk2 clutch -Stage6 clutch bell
I have gone through 3 spark plugs, 2 small end bearings, 2 pistons and 2 heads in 300 kilometers (180 miles)!!! When holding Wot for more than 5 seconds it just loses all power, doesnt bog but just slows down. I have tried changing the whole fuel system, jets, ignition timing, spark plug gap and everything, it rarely works well but mostly just does that. Im gonna order the 86 tpr kit now because i dont have money to buy more pistons.
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Post by Zino on Mar 28, 2020 9:47:19 GMT -5
One more thing to get ahold A cylinder head tempature guage . They dont cost much 20-25 dollars american on ebay for cheap one and a good tool to help you monitor cylinder health and keep things from blowing up .
It is not a replacement for good jetting and a well sealed up engine . When you ride you will see that it will settle in to certain ranges on my cruises at different speed ranges . when it starts to move more than 10 % out of those ranges ,I start to question why ?
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Post by christopher on Mar 28, 2020 10:33:33 GMT -5
Is the fuel bowl running dry at higher RPMs? That would cause you to go lean, over heat and seize up. Get a cylinder head temperature gauge so you know how hot you're getting. I aim for between 300°F and 325°F maximum. What rpm are you running at WOT? I try to keep mine under 10,000, it can do more and has once or twice.
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pewpew
Scoot Enthusiast
Posts: 254
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Post by pewpew on Mar 28, 2020 13:46:46 GMT -5
One more thing to get ahold A cylinder head tempature guage . They dont cost much 20-25 dollars american on ebay for cheap one and a good tool to help you monitor cylinder health and keep things from blowing up . It is not a replacement for good jetting and a well sealed up engine . When you ride you will see that it will settle in to certain ranges on my cruises at different speed ranges . when it starts to move more than 10 % out of those ranges ,I start to question why ? I have a stage6 gauge, cylinder head temps are max 67 degrees celsius
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pewpew
Scoot Enthusiast
Posts: 254
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Post by pewpew on Mar 28, 2020 13:47:54 GMT -5
Is the fuel bowl running dry at higher RPMs? That would cause you to go lean, over heat and seize up. Get a cylinder head temperature gauge so you know how hot you're getting. I aim for between 300°F and 325°F maximum. What rpm are you running at WOT? I try to keep mine under 10,000, it can do more and has once or twice. Im running at about 12000 rpm, should be more to get more power. When it starts to lose power rpms start to drop quickly, in about 2 seconds of keeping wot when it starts lose power, rpms are at 9000
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