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Bogging D7
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Carl
Birmingham
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April 8, 2021 - 8:59 pm
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Hello 

My d7 is running good revs fine is good in first gear. But when I give it any more than half throttle it bogs in second If I gradually increase throttle as the bike speeds up it is fine. Third it is worse than second but will still run fine if I gradually increase throttle as the bike speeds up. I have soaked airfilter in petrol, cleaned carb adjusted the air screw many times. The carb is a 375/4.  Not sure if It is jet needle or fuel.  I'm not sure on what jets are in it but if anyone knows what jet sizes It should be that would be great.

Carl. 

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Sponge
Lancashire (A chip shop somewhere near Preston)
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April 9, 2021 - 6:11 am
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If it is running fine at all other throttle openings then it sounds like your throttle slide cutaway might need to be checked or adjusted. Easy to do ...just pull it out and check the numbers stamped on the bottom. Let us know whst you discover.

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sunny
Norfolk
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April 9, 2021 - 7:14 am
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       375    is  it    ?     did  you  clean  the  2 tiny  jet holes   one in each  body part      &  bantams  run  rich  not  lean  

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Carl
Birmingham
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April 10, 2021 - 12:38 pm
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I have blasted every hole with air and brake carb cleaner. Tried every position on the pin works best at the top notch so that the pin is lower in the carb but still the bogg continues. 

20210410_121954.jpg20210410_122100.jpg20210408_200931-1.jpg

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mikef
Chatham Kent
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April 10, 2021 - 3:49 pm
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I'm pretty sure that the 170 main jet will be the problem. The D7 should have a 110 main.
Mike.

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Carl
Birmingham
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April 14, 2021 - 4:17 pm
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Hi i didn't read your post until after I purchased the 140 jet. I did test it today it is better but still not 100%   I have looked at a few different posts I have the pin on the second notch down from the top not sure if you count that as number 2 or 4. I've read some people say notch 2 some people say notch 4. Notch 2 in the Haynes it says. When I get a chan6ill change to notch 4 from too see how I go. 

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Number6
Lincolnshire
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April 16, 2021 - 7:15 pm
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Notches counted from the top.

What does the spark plug look like? First port of call to work out if mixture is right or not. E.g. sooty and black = too rich.

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

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sunny
Norfolk
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April 16, 2021 - 7:34 pm
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it service  sheet   510   dated  1959  to  66    says   the  needle  4 th from  TOP    thats  becouse  as i said befor     {  THE  375   IS  A        4 STOKE 
CARB   ]   and  dont  for get  to clean    the  2 tiny  jets   one  in  each  part  of  the  carb  or it  hard to  set  up  

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Carl
Birmingham
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April 20, 2021 - 8:39 pm
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So over the past week or so I've been messing about with the jets in my carb I changed from 170 to 140 and again to 110. But..... I went for a test ride and was really bad and couldn't ride it i then noticed bubbles of fuel coming from the crankcase just under the carb below the cylinder barrel. 

I have seen a video on you tube with the exact same issue. 

 

Is this likely to be the problem am I going to have to split the cases. Thanks 

Carl. 

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GlenAnderson
Dover
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April 21, 2021 - 2:07 am
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If your engine is doing that then yes, you’ll have to split the cases to find out why and rectify it. 

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sunny
Norfolk
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April 21, 2021 - 8:07 am
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your  engin was not  put  togeter  probly    ther  is  a bolt  secwens   for   engines     with  bantas  its  not  in   the  books so we  have 

to work  it  out  as we do  it    dont   forget  to  use a good  sealer   and  how to  use  it   

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stubaker58
Sunny Felixstowe
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April 21, 2021 - 8:31 am
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Hi,

just one point, the barrel is not a D7 barrel and the carb is a pre-Monobloc.  The advise about carb settings has been based on it being a D7.  Could be that the D7 settings are no good for the earlier engines (someone who knows will put us right).

Does look like a strip down though.

“There’s nothing new under the sun”.

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Carl
Birmingham
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April 21, 2021 - 9:53 am
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Hi that video is not my bike it just what I found on YouTube with the same issue but the bubbling is not as close to the barrel as that. It is directly under the carb.  I drained the carb while still attached to the bike because I forgot to put the brass spacer in where the float is. This must have broken down the sealer. Looks like I am rebuilding the engine. 

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sunny
Norfolk
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April 21, 2021 - 9:53 am
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the  4  photos  in post  no   4  show   a 375    .,.,    the  vidio  in post  9  shows  a  D3      we  dont  wont  any    leeks  at all   in  

any  system  on   any   vehcle      

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cocorico
Central France
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April 21, 2021 - 11:42 am
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From your description, I don't think your leak is from an area that should be pressurized (ie Gearbox or clutch scroll), so you may have a leak via crank seals into the gearbox, or a leak through the labyrinth seal of the crank case around the big end. Either way it involves splitting the engine.

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