HPI f3.5 engine tuning problems

[Zdragon71]

I've had this trophy 3.5 buggy by HPI for a couple weeks now. I broke it in using odonnells 20% race blend with 8% oil. Its ran great for breakin and several tanks after. Then i switched to byrons 33% with 16% oil and it ran one tank fine and picked up a bad low end bog. I figured it was the oil content so I've switched back to the odonnells race blend. I stuck a new lpr #7 medium plug in and she fired right up and as soon as it gets up to running temps around 210-230 it starts bogging at low rpm again. No matter how much i lean it it still does it and only at low end. As soon as it gets up it runs like crazy! Then after a couple of passes with it bogging at low end then picking up it stalls. I've went back to factory settings and retuned her at least 7 times and i end up back in the same spot. She will idle fine for a min or longer and as soon as i put her down and gas the throttle she shoots off like a rocket till temps get to good range and the bog comes back along with stalling. What am i missing? I'm the dang tech at my lhs and have suddenly lost my tuning ability on my new buggy. Someone help me work through this problem. You guys have never let me down yet. :\

 

[Zdragon71]

Also let me add that the filter on this buggy is supposedly waterproofed. It is totally enclosed minus one entry port facing back. I'm thinking since I've replaced both servos with futabas and they are not waterproof and i dont plan on running it in weather or water that getting rid of that air box and installing a normal 2 stage high flow filter would be better and may even solve my issues. Any thoughts?

 

[Nitro4910]

That's what I whould do, runnin them through the water & mud just makes a mess and invites problems to come say hi.

Put a good high flow on it & see what if does it.

Also look for any binding or bad bearings while your at.

 

[Zdragon71]

No binding anywhere and new bell and bearings. I'm gonna try the filter change tomorrow and see if that fixes it. Hell if the thing can't breath it wont run right. So I'm thinking that is just bad design on inclosing the filter anyways.

 

[eliansito]

Engine: Nitro Star T3.0 3.0cc (.18 cu in) 2.2h/ tunning

Hello, i have the same problem with my new HPI RTR e EVO with Engine: Nitro Star T3.0 3.0cc (.18 cu in) 2.2h , well i will check what i read from you and let you know my finding, Thanks to all you for been so helpfull

---------- Post added at 8:34 AM ---------- Previous post was at 8:28 AM ----------

i forgot, i did check all ,,, but not the filter, !!!!!! hope in there is the problem

 

[Zdragon71]

Elainsito did your EVO claim to be waterproof as well? And how long did your servos last or are you still running the stock ones? My steering servo went out on third tank of break in and then the throttle brake went out on the fifth tank.

---------- Post added at 8:45 AM ---------- Previous post was at 8:35 AM ----------

I expected to have to change them and even already planned on it but never expected to have them crap out within five tanks of fuel. I replaced them both with futaba S3305's. As far as the filter goes I'm thinking about just cutting the excess housing off and using a traxxas outer sock from there 2 stage filters. I've got a couple of them left over from my revo i sold. I'm also gonna give HPI tech support a call today and ask if this is an occurring issue with this buggy.

 

[Zdragon71]

Well just got back from post office. Had to send the engine back to HPI for them to check the compression and warranty it due to the sleeve being stretched already. I removed the engine from buggy and took flywheel off and with the plug still in it i could turn the crank over completely by hand with little resistance. This is after a proper break in and less than a half gallon of fuel through it.

 

[WinnersCircle]

I've had this trophy 3.5 buggy by HPI for a couple weeks now. I broke it in using odonnells 20% race blend with 8% oil. Its ran great for breakin and several tanks after. Then i switched to byrons 33% with 16% oil and it ran one tank fine and picked up a bad low end bog. I figured it was the oil content so I've switched back to the odonnells race blend. I stuck a new lpr #7 medium plug in and she fired right up and as soon as it gets up to running temps around 210-230 it starts bogging at low rpm again. No matter how much i lean it it still does it and only at low end. As soon as it gets up it runs like crazy! Then after a couple of passes with it bogging at low end then picking up it stalls. I've went back to factory settings and retuned her at least 7 times and i end up back in the same spot. She will idle fine for a min or longer and as soon as i put her down and gas the throttle she shoots off like a rocket till temps get to good range and the bog comes back along with stalling. What am i missing? I'm the dang tech at my lhs and have suddenly lost my tuning ability on my new buggy. Someone help me work through this problem. You guys have never let me down yet. :\

I think you are too lean on your HS.

Also, when you go up on nitro % you have to go up on your head clearance by adding head shims. I'll bet if you go back to the 20% fuel you will be OK. More nitro creates higher combustion pressure which will cause detonation (pre-ignition). This will RUIN your engine if you continue to run it this way.

My suggestion is either go back to 20% or add head shims to get the proper head clearance and run the 33% nitro.

Lee

 

[Zdragon71]

Lee i only ran 1/2 tank of the 33% and did go back to the 20 and the problem is the sleeve is stretched already and it looses compression. HPI already issued me a return number for it and they also stated that since the engine calls for 20-25% that i did not need to shim the head any. So I've already shipped it off to them to warranty for me. It lost its pinch with less than a half gallon of fuel ran through it after a proper break in. I havnt even gotten a full bash session out of it after break in. Guess i just got a dud from the manufacturer.

 

[Nitro4910]

Wow, that stinks. Hope they make good on it.

Sounds like they have a quality control issue.

 

[Zdragon71]

Well the way the tech talked over the phone he seems to believe there will not be a problem warrantying it due to the fact that i followed the correct breakin and havnt even had time to start abusing it any. So maybe they will just send me a new engine all together. Would be nice if they broke it in for me also.

 

[eliansito]

Elainsito did your EVO claim to be waterproof as well? And how long did your servos last or are you still running the stock ones? My steering servo went out on third tank of break in and then the throttle brake went out on the fifth tank.

---------- Post added at 8:45 AM ---------- Previous post was at 8:35 AM ----------

I expected to have to change them and even already planned on it but never expected to have them crap out within five tanks of fuel. I replaced them both with futaba S3305's. As far as the filter goes I'm thinking about just cutting the excess housing off and using a traxxas outer sock from there 2 stage filters. I've got a couple of them left over from my revo i sold. I'm also gonna give HPI tech support a call today and ask if this is an occurring issue with this buggy.

Hello Zdragon71, I just back, planning to practice tomorrow, and just my steering servo is going cryzy, also tomorrow will let you know about my engine, i did clean my two filter, ( they are not enclose) why you did not send your servos for warranty do we have the same servo ? HPI RACING SF-10W WATER PROFF ?

---------- Post added at 7:30 PM ---------- Previous post was at 7:17 PM ----------

Engine tuning problem,( the engine stall at high RPM?? bad servos too!!! HPI RACING SF-10W WATER PROFF ? I have HPI for many years, very good until now, the quiality drop at least in my new EVO3 !!!!??? Any comment please!!

 

[Zdragon71]

We had the Same servos and i called for replacements but they are back ordered. I bought futaba S3305s to install on both throttle brake and steering because i like futaba servos. I've ran them before and never had any issues with any of them. As far as my engine goes i tuned the idle problem out of it but at running temps its lost its pinch already and i now have sent it back to hpi as well. They are supposed to check it out this week and decide if they are going to warranty it. This is my first and last HPI buggy due to the engine issues and especially if they make me pay for repairs. I expected much better quality from HPI than I've gotten. And if i have to buy another engine I'm saving my money to buy a WERKS RACING B6 .21 to stick in this trophy roller so i can still use it for racing. I am not happy at all with my purchase of this trophy buggy due to all the problems I've had.

 

[eliansito]

Well the same, even I will try to keep it like as a bad expirience, or may get and OS engine, like FUTABA is for me the best in the market., definitly the quality drop, compare to the old ones, which I have two, locky you that can get the warranty !!!!!!!! I am in Mexico, and i bought it from Tower Hobbies, I am stock with it.??? COMMENTS !!!!
Thanks for sharing this with me, REgards Elian

 

[Zdragon71]

I bought mine from tower hobbies as well. You can get warranty help as well thru HPI. These buggies have a 2 years parts warranty against defects. Call hpi customer service with your issues my friend. See if they will assist you as well. 1-888-349-4474
View attachment 11661

 

[eliansito]

Thanks, I will try and keep you posted. but i am worry about shipping cost . and custum, ,, well ,will see.. In the mean time my T- Maxx is great.. i put a .18 TM OS. all is part of the hobbiy ups and donws.

 

[Zdragon71]

Yep. I have my tmaxx as well. Just too much power to control on a track with the picco engine and hitech servo on steering is way fast as well. Every time i touch the steering while under power the ass end breaks loose and it gets out of control. But its an excellent basher and jumps good. View attachment 11662View attachment 11663