Bike has 0 power under load when under 4000rpm?

[chuck hahn]

BR is the NGK race version of the B8 plug. And according to the parts fiche 2 of the MAIN JETS were wrong so according to the chart below i did use number drills and made them all the same. you got my number..call me.

https://www.jockeyjournal.com/threads/keihin-dynojet-mikuni-jet-size-cross-reference-tech.64769/

 

[chuck hahn]

According to the service manual (page 3-9) standard compression on a WARMED UP engine is 142 to 199. With a LOWEST LIMIT of 100. IF you arent doing the compression check with the throttle wide open redo the test. IF you did have it wide open then your compression numbers as posted indicate its time to rebuild that top end. Also the parts fiche says the main jets are #110.

By rebuild i mean measure bore wear per service manual too...not just throw new rings on the pistons

 

[Grimly]

BR is the NGK race version of the B8 plug.

The R there in an NGK denotes that it's a resistor plug, but NGK do a range of racing plugs. Istr an odd R in some plug types that did denote Racing use, but what make it was, I don't recall.
https://www.ngk.com.au/technical_info/racing-spark-plugs/

 

[chuck hahn]

An email from NGK directly stated its their race series that replaces B8ES,that how i remembered it. i think the thread was about NGK rumor about going out of production. May revisit tat thread to read the response to the inquiry i sent them

EDIT.. I STAND CORRECTED. It does denote a resistor plug.............


https://www.thegsresources.com/_for...k-plug-shortahe&highlight=spark+plug+shortage

 

[Cipher]

According to the service manual (page 3-9) standard compression on a WARMED UP engine is 142 to 199. With a LOWEST LIMIT of 100. IF you arent doing the compression check with the throttle wide open redo the test. IF you did have it wide open then your compression numbers as posted indicate its time to rebuild that top end. Also the parts fiche says the main jets are #110.

By rebuild i mean measure bore wear per service manual too...not just throw new rings on the pistons

have the valves been set to spec. Cant seem to see that anywhere

 

[Guest]

I have a 82 gs750 with the exact same problem it used to be a perfect running bike until the previous owner cleaned the carbs. Broke the pilot jet off in no4 and had to put a new carb on. I found 2.5 turns out on the mixture is good. starts perfect throttle doesn't hang no back fire. From what i have read on your post it has to be a carb issue as it is the only thing that made this bike run bad. Will be interested how you get on.

 

[zed1015]

The R there in an NGK denotes that it's a resistor plug, but NGK do a range of racing plugs. Istr an odd R in some plug types that did denote Racing use, but what make it was, I don't recall.
https://www.ngk.com.au/technical_info/racing-spark-plugs/

You are correct.
The code for an NGK racing plug starts with an R but confusingly they also have a range of race plugs that end EG.
The R in BR denotes a resistor plug.

 

[Rijko]

Okay so I did a compression test and here's what I found. 1 - 110 2- 105 3- 101 4- 118.

According to the service manual (page 3-9) standard compression on a WARMED UP engine is 142 to 199. With a LOWEST LIMIT of 100. IF you arent doing the compression check with the throttle wide open redo the test. IF you did have it wide open then your compression numbers as posted indicate its time to rebuild that top end. Also the parts fiche says the main jets are #110.

By rebuild i mean measure bore wear per service manual too...not just throw new rings on the pistons

Why is that, Chuck ?
Ofcourse i agree #3 @ 101 is not high, but still within service limits.

But if performed on a cold engine that would mean compression is higher.
And if performed with throttle closed, also means compression is higher.