1995 HX 717 motor question

[orbit398]

Rebuilt the 717 motor (bored/new pistons/rings etc); rebuilt carbs, all new gas lines/filters. It starts and runs great. But has one weird issue. If I run it pretty hard for a while (going up a river for example or across a lake), when I slow down to enter a no-wake zone or area to park and party with others, the throttle becomes non-responsive for a bit. The motor doesn't die, it just doesn't go when I push the throttle. So I have to push/release the throttle many times for it to finally 'go - run normal again'. Plugs look great. Very odd and not a big deal for me, but when I have others ride it, they'll have issues. So, just wondering if anyone has suggestions or items to check.

 

[tomanycars]

Did you put a new fuel pump in

 

[orbit398]

yes - in the Mikuni carb kit, there are two small round clear plate things that are part of the gas pump design. I replaced both.

 

[mikidymac]

Could be too much fuel from needle and seat leaking. Test leakdown on the carbs again.
Could be too much water in the muffler, do you still have all the extra hoses going to the rear water-box?

 

[orbit398]

Has a brand new 1.2 needle and seat so hoping not that. What is the leakdown test on the carbs? Is this the popoff psi test?

I reworked this HX the same time I did the XP. So not really following you on the 'extra hoses to the rear water-box'. I took a pic of what is looks like under the rear cover.

 

[mikidymac]

Basically you make sure the carbs hold about 10 psi after they are back together to make sure the needle and seat are not leaking.
It is in the carb rebuild thread.

The later HX's had a bunch of extra hoses that dumped more water into the water-box to make them quieter but had some hesitation when trying to clear all the extra water out. Yours does not have the extra water hoses.

 

[orbit398]

Carbs hold pressure fine, so assume the needle/seat are working as designed.. Just took it out yesterday and noticed if I hold it wide open for a bit, it seems to be running out of gas. Up to say 3/4 throttle, engine runs great, but if I go beyond that with a steady throttle for a little bit, it starts to bog. If I back off, then I am thinking the gas flow catches up and it runs fine. I have a small plastic/paper element inline auto gas filter so perhaps the flow through it can't keep up at full throttle. Being the gas line has a water trap/filter already, it is wise to even have an additional gas filter? Anyway, I just purchased one of the K&N glass type filters like I have on my XP and will replace the plastic one. Guess I'll see next time out if that had an affect.

Another question. This HX engine has been bored out 1mm over, last size to bore. I still am running the 137.5 main jet. Could that be an issue? Perhaps I need to go up in size due to the engine cylinder cc's have increased.

Any suggestions appreciated.

 

[mikidymac]

DO NOT run any inline fuel filters. The only thing you should be running is the OEM strainer or you will run lean on top end.

 

[orbit398]

DO NOT run any inline fuel filters. The only thing you should be running is the OEM strainer or you will run lean on top end.

DO NOT run any inline fuel filters. The only thing you should be running is the OEM strainer or you will run lean on top end.

thanks for the reply. when I purchased it there was an inline filter so just put a new one inline when replaced the old grey hoses.....