CB 200 carb tuning? + Gasket quality?

herre

herre

New Member
Hi,

Recently my cb200 cylinder head gaskets started to leak. Figured it was time for a complete revision (after 25000 km). So I took the entire engine apart, changed all the worn parts and put it back together. I also changed the carbs to some cheap but ok 20mm ones. The stock 18mm carbs were all rusted up. Last weekend I got it running. It actually started quite good and fast. But its revving up way too much.

Here's what I did:
-Changed jetting on the carbs to 98/35
-Air screw 1,5 turns out, Slow run 3 turns out
-Gas needle on stock setting (clip in the middle)
-Put the carbs on (not synchronized yet...)

Here's the video of the first start:
http://www.youtube.com/watch?v=hXnLsYrSeiU

How do I continue? Why is it revving up like that? Too much fuel?

Oh and one more question: I put in 15w40 semi synthetic as for now. I'll change the oil when the carbs are tuned. Newly rebuilt engine needs a "flush" anyway right? But what oil should I use? Is mineral oil better for old engines? Can semi synth harm the engine?

Any help is appreciated!
 
Re: CB 200 carb tuning? + What oil?

Revving high can be any number (or combination) of several reasons.

Go through and check the following:
*Idle screw adjustment - Make sure the idle screw is set accordingly
*Timing - Advanced timing means higher revs
*Vacuum leak - Check the carb boots to ensure no air getting by
*Incorrect jetting
 
Re: CB 200 carb tuning? + What oil?

For oil, stick with 10w-30 or 10w-40 mineral oil for the first hundred miles. Change again at 500 miles with the same stuff. At 1000 miles change it a third time to whatever works best for your bike. I hear good things about Shell Rotella 5w-40 and 15w-40. Haven't tried either, myself, though.
 
Re: CB 200 carb tuning? + What oil?

Allright thanks man! Should I change the oil as fast as possible then? Or is it ok if I leave the semi synth in to tune the carbs? (All gaskets have been replaced).

Oh and, any tips on how to check the carbs for air leaks? Seems to be running pretty steadily though. I've had air leaks before and most of the time when that happens it revs up and down, never steadily at higher revs. And is 98-35 a good jetting for 20mm's on a cb200? If not should I go bigger or smaller?
 
Re: CB 200 carb tuning? + What oil?

Hey GertJan,

Welke carbs zijn dat? Ben ook bezig met een 200 maar kan nergens 20mm's vinden voor normale prijs.

thnx!
 
Re: CB 200 carb tuning? + What oil?

Bert Jan said:
Hey GertJan,

Welke carbs zijn dat? Ben ook bezig met een 200 maar kan nergens 20mm's vinden voor normale prijs.

thnx!
Click to expand...

Het zijn 20mm keihin replica's. Chinese goedkope stuff. Maar ik zit op een studentenbudget dus moet het goedkoop houden. Werken doen ze tot nutoe wel ;).

Heb ze hier gekocht: http://www.mini-bikes.be/index.php?page=webshop&p=webshop

Vergeet er wel niet de juiste sproeiers enzo bij te kopen.

Any more tips on the bike guys? I've got the entire weekend to work on it now.
 
Re: CB 200 carb tuning? + What oil?

use a bit of carb cleaner and spay it on the manifold where it attaches to the carbs and the engine, one side at a time if it bogs down you have an air leak, are you using the choke to start it up? If so will it stay running after a min when you turn the choke off? If you can start it with no choke cold and its idling that high with no air leaks you want to adjust the idle speed screw, and your a bit rich, more than likely, if it will idle with no choke at a lower speed and you give the throttle a quick twist(like a short blip maybe 1500rpm change) and it drops back down without hesitation your okay, if it is real jumpy at idle bouncing around more than 50-100 rpm at idle your more than likely lean

sorry for the book, haha hope that helps some
let us know how it goes
 
Hey thanks man! I got the carbs tuned more or less but that'll help me further! New problem however: still had an oil leak at the head so I got it resurfaced. And now I'm wondering what gaskets to get. Are these http://www.ebay.com/itm/REPLICA-TOP-GASKET-SET-TO-SUIT-HONDA-CB200-CL200-76-79-/360440176060?pt=UK_Motorcycle_Parts&hash=item53ebe89dbc#ht_1489wt_1163 good quality? Or should I get some copper gaskets from copper gaskets unlimited?
 
Did some googlin' and found out I should probably go with OEM gaskets, but one more question before I slam the head on there again: do I need to do anything to prepare the head gasket? Gease up the non metal part? Or should I just put it on there?
 
Paper Gasket OR Liquid Gasket
NEVER BOTH!!!!

(carbs ok? merk je veel verschil in power? en zijn het die van 29e en welke sproeiers heb je erbij?)
 
Aight, thanks man!

(carbs ok ;), nog niet zo veel gereden maar hij trok toch beter (meer power in de hogere toeren), heb er wel sl175 spruitstukken bij ook, sproeiers zijn voor zover ik me herinner 98 en 35 geworden, ik controleer dit weekend nog eens)
 
Regular head gasket should not leak. What oil seals (O rings) are you using around the dowels on the outer studs?

We lap all mating surfaces on a sheet of wet or dry on a flat surface using kerosene or WD40 as a lubricant/cutting oil. That's a cheap easy way to be sure than surfaces are flat.
 
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