OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Honda Engines Honda GXV160 giving slight dark smoke puff when revving?

Hi Tyler,

Much thanks in advance for the reply & assistance - its very much appreciated. :-)

Yes isn't doing this, so thank you for eliminating.

The current plug was an NGK BPR6ES. I've cleaned it regularly but upon removal it had far more carbon on it than I've previously seen. SO a tad unusual.

In trying to adjust the carb last season, it's possible I got it well off where it should be - as mentioned I was using a cheapish RPM monitor and couldn't really find improvements from changing. So unsure if my attempt to get back to 'default' levels have been less than ideal.

I will try and grab a few of the NGK BPR5ES as you have recommended - thank you.

I will see how I go - the airfilter-snorkel assembly is a factory one that i removed from a GXV160 engined Masport that I had (subsequently sold off). I only run the large bottom single airfilter in it rather than the two that one can do. I use it purely to ensure that the air intake is higher up and well away from the dust zone. The top snorkel intake only has a layer of flyscreen inside it - so offers very little to no resistance to the airflow at all.

So valid point - but if I'm only running the single airfilter, even with the snorkel I can't imagine this would really make it much harder for the engine to draw the air in vs just the single bottom filter. I'll note that I've run it like this for 5yrs or so - and not had this problem occuring previously, which makes me think that it's unrelated to the snorkel with single filter. But is a good catch by you.

Ok will do - I just happen to have a cheap and cheerful endoscope so I will see what I can ascertain but I suspect judging by the sparkplug that it's going to be grubbier than I'd have hoped.


Point taken - just curious and I know this is a point of contention for many - but why the 98RON recommendation? I always use 91RON on anything that specifies it and ensure that fuel stabiliser is added to the storage container as soon as I get it home. Fuel stored in a flammables cupboard thats in a cool area.

I've used injector cleaner in it very regularly BUT I suspect it might have been rubbish - which I kind of knew being that it was a Valvoline product.
I will keep a look out for some of those ones you advised. Much thanks for that.

Just trying to find one of the P.E.A containing fuel injector additives - but obviously value depends on how much of the good stuff they put in the additive - as many seem to have only a tiny amount:

Caltex Techron Concentrate contains 15-20% Polyether amine
Rislone Hy-per only as 0.1-1%! Seems very dodgy as they openly state that it contains P.E.A but has very little of it!
A well regarded US one Regane Gumout has 10-30%
The STP one is very confusing, seems to have a bunch of stuff but no pure PEA but some similar ones.
If you can find it Red Line® SI-1 Complete Fuel System Cleaner has apparently the highest at 28-34%.

Annoying that a lot of ones seem to either have a very small amount - which would have likely no benefit or seem to use very tricky names which make it unclear if they have it at all.

Amazing when you look at the SDS that so many of them are very questionable in benefit i.e all kerosene or napha etc. All the Australian brands were really shitty when you looked into them - Penrite, Nulon etc very low levels of PEA.

PS. FWIW the best value by far was the Redline SI-1, contains 28-34% PEA - so you could use much less of it for same effect. This was the cheapest i found for a single bottle: https://www.ebay.com.au/itm/186140803269

@Tyler,

Just curious - you've recommended the BPR5ES rather than the BPR6ES I have been using - I know this is the next 'hottest' compatible plug on NGK's scale - would you feel if going to a 'hotter' plug will assist, is moving a single increment likely to be discernable as opposed to going with the BPR4ES etc?

I wouldnt go to a 4es but a lot of gxv160s take a 5es. Who knows if it makes a difference but it stands to reason any hotter plug will help reduce deposits and give cleaner burn

Tyler,

Cheers for clarifying - used one of my rare trips into town to pick a BPR5ES up, will toss in and when it dries up a tad here (as our Eastern seaboard drought was broken over the last few days) will report back thoughts.

Ok - as recommended by Tyler, I got out the very cheap and nasty endoscope I have - inserted it into the mower this morning but alas I really could not discern much at all - it's just such a cheap one that the focal length seems to struggle with showing much.

What I can safely say though, just from eyeballing it through the hole myself using a torch, is that there's a significant amount of carbon in the cylinder - certainly more than I've seen previously.

Due to the recent break of the dry spell here - I'm going to have to mow today - I'll pop the BPR5ES plug in and see if that assists - the PEA injector cleaner is onroute - but I don't know if I'd be recommended using something more robust to remove some of that built up carbon in a separate process?

I'm still unsure if I should adjust the carb screws to make it a tad less rich or if this oil 'blend' I put together from left over odds and ends, has somehow played a part in this.

Hmmmm ok just did 45mins or so chipping away at the 3500m2 of surging Kikuyu....alas the BPR5ES doesn't seem to have changed much, still getting puffs of black smoke when I hit a thicker patch of grass. I'll yank the plug when I go back out but I suspect it'll already have a good deal of carbon on it.

I'm suspecting it's either the carb settings or perhaps something odd has happened with the oil blend and its caused problems - when everything I mixed did have a working/hot weight of 30 or above - but it seemed surprisingly thin when I took checked the level before starting. Alas due to my diligent mixing I have around 6L of it.

I might buy a litre of bog standard 10W-30 and see if that still has the issues - if nothing else I'll eliminate it as the problem.

Any other ideas welcomed - dunno if I should try and adjust the carb now or if moving too many variables at once just confuses isolating the problem?

Just finished the front 'yard' 90mins straight mowing - the pleasures of living on acreage thats not able to be done by rideon. Checked the plug before starting and sure enough it was filthy, really no difference at all from the BPR6ES in terms of the amount of carbon on it.

I removed the thin foam prefilter on the airfilter to provide a tad moree airflow - as I'm just trying the 'easy' stuff first -. ANyway the amount of smoke is just as bad as ever - might even be a tad worse to be honest - if I have the engine at idle RPM and then accelerate with no cutting load at all there's quite a big shot of black smoke that shoots out - very pronounced.

SO I think I can eliminate the plug (though I think the hotter plug is a good idea anyway), I think the airflow to the carb isn't the issue, so eliminate that too.

That leaves the carb settings, oil and perhaps anything else as the things to try and alter/adjust?

Any ideas welcomed. :-)

PS. I likely need to find the cause of the smoke first - but if there's a best way to reduce/remove the carbon thats built up in the cylinder head etc - please feel free to let me know - prefer something non-mechanical (i.e not have to open cylinder head completely) but dunno if I can remove the exhaust outlet and flush/soak with carb cleaner etc? Again I won't do until I've reduced the smoke as otherwise kinda pointless.

As already mentioned black smoke means a rich mixture, too much fuel or not enough air, nothing to do with the sump oil (unless you have tipped the motor the wrong way and blocked up the air filter with oil).

Is the choke opening completely when off?

Someone may have used some wire to clean out the main jet, or the two holes in the bolt which holds the float bowl onto the carb, and enlarged the bores. The fuel inlet needle attached to the float might not be seating properly.

Just some thoughts, I have found those motors tend to be not too fussy with the fine details.

Hi MowingManiac, thanks for your reply.

Defintely didn't tip the wrong way - learnt that many years back the hard way. Airfilter checked this morning - no issues with it at all.

I'm unsure of this offhand - no issues starting it first pull as has always been the case. I could check but I assume this'd need the carb removed from the plastic body - which is a bit of a PITA, seems all the rods etc are moving properly, carb is a tad grubby on the outside but as I'm very careful to always use stabilised fuel, shitty carb cleaner in the fuel (better stuff onroute thanks to Tyler's tip) and turn off fuel tap prior to turning engine off - I'd think it should be pretty spotless inside.

As I've had it nearly from new and certainly never done this I'd think it can be ruled out - but if you feel the carb needs to be pulled apart and checked let me know. Sounds like I'd only have to remove the fuel bowl to do this?

Thats been my experience as well - it'd worked very well for years and then this just started occurring. Part of my reason for thinking it might be the oil blend was that was one of the only variables that changed around the time it started occurring - but again the oils put in were all good quality and essentially when totalled about the weight Honda states 10W-30.

Is a puzzler.

I have had issues with some of these Hondas for some reason with the choke not coming off and I have had to put a small spring on them to ensure the choke fully opens. And then with these vise versa, you have to ensure the choke fully closes or they will not start. Sometimes they can be a fine balancing act to get right

Yeah no choke issues for this one super easy to start right from the first day I had it.

Unsure what the next thing to try is? Smoke has definitely gotten worse from when first noted on here.

I have it running 'better' now.....Red Line SI-1 fuel cleaner (recommended by Tyler) arrived. I will start using.

Wondering if it's worth trying to remove some of the carbon build up that seems to be in the cylinder & piston head? A mechanical disassembly would seem a tad much - but I've read spraying carb cleaner down sparkplug hole, allowing to soak can loosen and assist removing it.

Any thoughts on if it's worth removing the carbon & if so how to do welcomed. :-)